Renix...dammit

OK, I am new to the XJ world, and having some issues.....

1988 Cherokee 2dr, 175k miles, rescued from the crusher...

Idle is decent, but varied...sometimes high, sometimes low, no rhyme nor reason for either. Good top end..very, very good full throttle acceleration. Off idle, however, is a different story. Slow acceleration is OK, but anything between Grandma and WFO results in hesitation, bucking, and backfiring through the intake......

Here is what I have done....

New plugs, wires, cap and rotor...
New Air and Fuel filters...
TPS has been adjusted, and tests good...
MAP sensor replaced...
IAC cleaned, and functioning...
Exhaust replaced...
Checked vacuum lines, and no apparent leaks...
EGR is disconnected, prior to my purchase...
Air Intake Temp shows no difference whether hooked up or not...

My plans tomorrow are as follows...

Replace Coolant temp sensor...
Trace and replace all vaccum lines...
Recheck TPS...
Check O2 sensor...

I am wits end..the truck has an insane amount of power at full throttle, but driveablity is terrible...

Anything I've missed?

All are classic signs of a faulty EGR, but really you just need to go over everything and check it. Start with the grounds and connecters.

Do you have the RENIX FSM?

I have the RENIX manual on my laptop, been reading it some, but damn, its dry...

On the EGR side, what do I need to look for? When I got the Jeep, the EGR module on the fender had no vacuum lines going into it, could be a clue, I suppose.

These two should help you out....

http://jeepgarage.free.fr/OWN/egr%20function%20testing.pdf

http://jeepgarage.free.fr/OWN/egr%20system.pdf

x2 on the EGR valve.

Also, volumes have been written about bad grounds on the Renix jeeps. i was not sure I believed all I read about the subject; I was positive that I had a sensor breaking down somewhere....until I added a hefty additional ground cable over the existing strap and another from the negative post of the battery to the front end sheet metal. Solved my problems.

OK...update time...

Replaced ALL the vaccum lines from the intake...
Adjusted TPS as well as I could, was only getting 4.65VDC input..
Hooked the EGR back up after cleaning it..
New 1ga ground cable with auxiliary 4ga cable from battery ground to fender..

I didn't get a chance to replace the Coolant Temp Sensor, will try tomorrow night...

Result?

Noticeably smoother idle, much more power in all ranges, however, I still have a slight flat spot off idle, and an occasional backfire through the intake. Its not nearly as bad, or nearly as often, but its still there, and its driving me nuts.

Just a hunch but did you check the vacuum tube from the Throttle body to the MAP sensor to be unclogged? Ive seen one do the same thing with a clogged vacuum tube from the MAP..

Yes, the vacuum line from the TB to the MAP sensor was replaced as well.

Looks like my next step is going to be replacing the Coolant Temp and Air Intake Temp sensors..Maybe a new EGR valve...and solenoid..

Your idea of a heavy ground wire between chassis and negative battery post is a good one....my symptoms improved when I added a heavy ground wire over the existing strap between block and chassis. My reasoning was that the sensors are grounded thru the block. Keep chasing it !!