Startups

My 87 XJ (4.0 AW4) has a hard time starting up. It cranks real nice, nothing to do with the battery. However it takes a whole lot of cranking to get it going. It gives that little renix rev on startup, the rpms go to about 1500 then decrease. The rpms drop close to 500, then the jeep stumbles. It dies out if you don't give the skinny pedal a little punch. After that it runs perfect. Startups become normal after you get through that. Letting it sit for a few hours repeats the process.

Any advice?

I let a couple of drops of light oil drop behind the IAC piston/plunger, cleaned the EGR valve seat and cleaned the orifice at the top that goes through the drivers side of the TB. There is a metal cap about half way down the drivers side of the TB, that you can pry out and use a Torx to adjust minimum idle(after cleaning the passageway out). Minimum idle changes with the the motor temp. it's hard to get it just right at all temperatures. Keep track of where you started adjusting, in case things get too far off.
I did mine by trial and error, but a better method may be to let the IAC seat all the way, on a warm motor and adjust the minimum RPM with the Torx screw on the drivers side of the TB.
I also tried adjusting the throttle stop for minimum RPM, but every change of the throttle stop changes the TPS a little.
TPS adjustment, MAT and others also have an influence on idle. Mine changes from closed loop, to open loop pretty darned quick. It has been said it needs something like a 140 deg coolant temp. for the computer to switch to open loop, but mine changes way before that.
People have said the Renix has no memory, but after unhooking my battery, things change noticeably with mine. Who knows?
Try unhooking one of the vacuum lines on the front vacuum tree on the intake manifold, just to see what happens, if it helps, you probably need a little more air at start up. Unhook the vacuum line to the EGR valve and plug it for a test.
Old_Man recommended checking the values for the engine temp. sender on the lower left of the block and the MAT sensor, which I did. It's a good idea, just to know for sure.
Cleaning connectors and grounds has always helped mine to run better. All of the connectors on the lower left of the block, have a profound influence on how things idle and run and are rarley cleaned. I actually used a very small brush and a quality contact spray on mine.
I know the list is long, but there are a whole lot of inputs for the idle. Not to mention the state of your tune up.

8Mud has most of it covered. I think the best results I ever got on my 87 were from taking apart and cleaning the connectors from time to time. It seemed very sensitive.

Another thing you should look at is the likelihood that the check valve in the fuel system is leaking down when it sits. That may be why it starts better after you've been running it. Next time you go for a cold start, try turning the key on, leave it on as long as you hear the fuel pump run (about 5 secs or so) and only then crank. If this improves start times, you have at least a partial answer (on an 87 you could have several things added together too, of course). You can go a very long time without fixing this, if you just make a habit of waiting before you crank. It has no effect on running once you're started. On the first cold start of the day you might even want to turn the ignition off then back on, to cycle it twice.

Matthew Currie said:

Another thing you should look at is the likelihood that the check valve in the fuel system is leaking down when it sits. That may be why it starts better after you've been running it. Next time you go for a cold start, try turning the key on, leave it on as long as you hear the fuel pump run (about 5 secs or so) and only then crank. If this improves start times, you have at least a partial answer (on an 87 you could have several things added together too, of course). You can go a very long time without fixing this, if you just make a habit of waiting before you crank. It has no effect on running once you're started. On the first cold start of the day you might even want to turn the ignition off then back on, to cycle it twice.

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This would be like priming it right?

I'm going to check the things that 8Mud mentioned.
As far as the tuneup. SP wires are good, SP's are good, distributor cap and rotor are fine.

I'll probably switch out the fuel filter for good measure.

Anyone else?