Studdering and stumbling

so about two days ago, my truck started studdering like a flat constant miss, stumbling like i was runnning out of gas and even has an intake back fire once or twice. then for what ever reason it will start chugging like usual also two days before that i hooked up a home made intake tube and cone filter, moved all the lines closer to the actual TB,so i thought maybe the sending unit floater had tweaked and made it contact the top of the screen off the bottom of the FP, has happened before giving me a false reading on the gas guage, so i pulled it, and it was, so i shaved a little rubber off the screen cleared just fine, and i was just about empty, so i threw in two gallons to make it to town(16 miles 2 gallons is plenty, drove fine, filled it up, and leaving the gas station it stumbled and died, started up and drove fine, made it about a mile and stopped at a drive thru coffee, didnt shut it off, and when leaving i made a semi hard u turn to leave the drive thru, and it stumbles and dies yet again, starts right up makes it the 16 miles home and is fine for now. Tomorrow i plan on cleaning and or replacing all my engine grounds to start, what else could cause this,could oil be coming in from that breather and just making it into the manifold? i should mention in the last 4 months i have replaced:
TPS
IAC
CKS
ICM
Coil
cap rotor, plugs/wires 6 months ago
fuel pump
I searched.

the fuel filter canister isn't on your list...

Renix TPS adjustment procedure performed?

check your 02 sensors. on my 98, when the 02 sensors went bad/shorted, it started bucking/stumbling like crazy and backfiring in the manifold.

I found that it was my front 02 sensor shorting out. Replaced it and back to normal.

My 88 has done that a few times, with the intake backfire it sounds like the CPS or the CPS wiring. Even a seriously dirty CPS, oil covered and maybe full of metallic residue. Had one CPS that I washed off and it seems to work fine now (?????).
Something seriously wrong with the MAP can do almost the same thing, less the intake pops.
Like mentioned a bad O2 sensor can lean out the motor and act almost like a normal fuel delivery problem. Though in my experience (in the Renix) it shows up first at a round 2000 RPM first, pops and bucks. Normal fuel delivery problems usually show up first when you are using the most fuel at high speeds.
Have you checked your fuel pressure and volume? What shape is the fuel regulator in? I've only seen one bad fuel regulator in the 20 some years and that was a leak.

O2 is 3 weeks old and fuel filter was replaced when i did the pump, totally forgot about those, whats the procedure to test the regulator? its not leaking, and if the MAP is bad, just un plugging it should get me to the parts store correct?(40 miles round trip) Regarding the cps are you talking crank position sensor(cks) or cam position sensor il clean both regardless, think its possible to have lost a tooth on my distributor gear?

also il be busting out the chilton to set my TPS with in spec.

89RockHeep said:

O2 is 3 weeks old and fuel filter was replaced when i did the pump, totally forgot about those, whats the procedure to test the regulator? its not leaking, and if the MAP is bad, just un plugging it should get me to the parts store correct?(40 miles round trip) Regarding the cps are you talking crank position sensor(cks) or cam position sensor il clean both regardless, think its possible to have lost a tooth on my distributor gear?

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Crank position sensor (or whatever they are calling it this week). On the driver side bell housing, near the top. There are some pictures if you use the search function to find them. The CPS wires have often been known to flop over onto the exhaust manifold (in the rear) cook and have sporatic shorts. You mentioned yours crapped out during a sharp turn.
If the MAP vacuum is unplugged it will barley run. I don't think I've ever tried to run one with the MAP electrical unplugged. Likely to run like chit if at all.
I've found way more flaws in the grounds, connectors and wiring than I ever have with the sensors themselves.
Unlikely to be a chipped tooth in the distributor, though I have seen a broken distributor gear pin before. Push the distributor shaft to the side, this will give you an idea of the side play. Inspect the cap for damage to the poles and the rotor for physical damage. Pull the distributor shaft up, there is often a lot of play in this direction, but rarely causes much, if any grief. Unless the shaft has so much wobble the rotor hits the cap poles, you are unlikely to notice much, though it may idle a little rough.
Fuel pressure specs and volume test are in your Chiltons.

The O2 sensor has a heater circuit, that is powered from a relay in the block of 3 or 4 near your battery. The wiring for the O2 sensor has a tendency to cook on the exhaust manifold near the front of the motor behind the power steering pump. I had mine cooking on the manifold and the XJ was acting like it ran out of gas on the interstate.

The CAM position sensor really doesn't do much (in my experience) in the Renix, I once forgot to plug mine back up and drove around for months without even noticing. I usually notice most any change or new sound in my Renix.

ok just went out to test somethings, started up ran like shit, unplugged o2 continued to run like shit, its missing and struggling up through the rpm range and when you give it some gas right off the bat, it will hesitate, and if you try to move it in drive now, it will barely move, then it will just sit there at like 100-200 rpm for a few seconds and die no visible damage to cps wiring, or o2 wiring, i do have a spare cps i can try.ive always had high idle issues, not much though, 1500 in park, 1000 in drive, so was never terribly concerned about it.

il also mention that the covering on my ground wire is severely cracked and missing alot, but i have another ground running from the motor mount to the battery, il replace it none the less, but im getting concerned at this point.

89RockHeep said:

ok just went out to test somethings, started up ran like shit, unplugged o2 continued to run like shit, its missing and struggling up through the rpm range and when you give it some gas right off the bat, it will hesitate, and if you try to move it in drive now, it will barely move, then it will just sit there at like 100-200 rpm for a few seconds and die no visible damage to cps wiring, or o2 wiring, i do have a spare cps i can try.ive always had high idle issues, not much though, 1500 in park, 1000 in drive, so was never terribly concerned about it.

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High idle would point me towards the TPS first, then a fairly serious vacuum leak second. Though a vacuum leak is unlikely to cause the low idle and crappy running.
Ohm test your coil to cap wire, double check that the coil to cap wire contact ends are all the way in.
The harness where it runs down the front of the motor is hard to see, where it can touch the exhaust manifold almost impossible to see. You may want to unhook the cable hold down on the side of the block, pull the harness up and down to inspect the places that can't be seen. A flashlight and a small mirror at the very least.

I'm still leaning towards a CPS problem (but like I've said, what you describe can have many causes). If all else fails you may have to bite the bullet, pull the connector off of the ECU, jump the CPS pins with a paper clip and ohm test the loop at the CPS connector, just to make sure the wiring isn't screwed between the CPS connector and the ECU.
I'd also ohm test the CPS, new doesn't mean good. I've had a CPS right out of the box that was junk.
Alldata does a pretty good job with the Renix electrical. There component electrical diagrams are much easier than full schematics. The sensor and component tests well written up, though sometimes a little difficult to navigate. Worth the money IMO.

for what ever reason, i just started it and now its running fine again. now im getting scared, possibly the computer? im about to go get a free cherokee that couldn pass smog, so il have spare parts

and exactly what harness are you referring to that does down the front of the block?

89RockHeep said:

for what ever reason, i just started it and now its running fine again. now im getting scared, possibly the computer? im about to go get a free cherokee that couldn pass smog, so il have spare parts

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Start shaking harnesses and connectors and see what happens.
I had a CPS that would do that, it depended on the temperature. When the CPS got warm the motor would run like chit and often fail to start. Cold it ran fine.

to add to the list of symptoms, i backed it down my drive way about a hundred yards, while it was running ok, and drove it back up, gettin on it, the engine doesnt have the power it normally does, and seems slow at building rpms.

i shook that harness you were referring to, and the idle changed.