stumbling, random stalling

'91 4.0/AW4/NP231/D30 8.25 3:55 ~194500 miles

About 2-3 weeks ago I was coming to an intersection after driving for about an hour (20-30 mile commute to school in Boston). Randomly, the XJ just cut out on me while idling. I tried starting it back up and it sounded like it was starving for fuel or something because it was turning over and almost catching. After 2-3 more times of working the gas and everything, I gave up. About 5-10 minutes later, I fired it up and it started no problem and hasn't given me a problem until today.

So today I pull into a parking lot after driving for about 5-10 minutes and put it in reverse and go to back into a spot. It starts stumbling for about a second before I shut it off. I come out of the store and try to start it again with the same symptoms; it turns over and almost catches. A couple of times it turned over but idled for a couple seconds at like 200 RPMs and then died. So I leave it alone for about 5-10 minutes and it fires back up no problem and I've driven it for the rest of the day without a hiccup. I've cleaned the throttle body, and I'm leaning more towards the CPS but if anyone has a step by step as to how to clean the IAC I'd be tempted to just try that first. Sorry for the long post just trying to be very specific, thanks.

It kind of sounds like a sticky IAC. Spray a few drops of light oil beside the piston. Put a drop of synthetic motor oil next to the piston and let it run behind the piston (there is grease behind the piston that gets old, dirty and thick). With the engine running and the IAC installed, spray a little PB blaster into the IAC port and work the throttle a little to get the IAC moving around some. I do this with my spring and fall maintenance, on both my Renix and OBD I XJ's. It avoids a lot of problems later.
A sure sign of a sticky IAC, is occasional *high* or low idle. And the idle will usually reset to near the proper level, when the motor is turned off, then on again. The shutdown relay, seems to do a better job of positioning the IAC (probably a bit more voltage), than the computer does, when it gets sticky.
If the 91 has an EGR (?) that's probably the second thing to check.
A word of warning, pulling on the piston can ruin the IAC, if pulled just a little to far, the threaded rod (connected to the bottom of the piston) will pop out of the motor or stip the gears. Trying the IAC with it out of the TB (electrically) can also ruin it, it can launch the spring and piston at least 6 feet. Trying to put it back together again (after seperating the piston and rod from the motor) can be an iffy thing. Messing with the IAC to much can be an an expensive mistake.
A new IAC, should be installed carefully, if the piston is too far out the piston rod can bend while tightening the screws. They usually come positioned near full retracted, but not always. Something to look at. If the new IAC comes with the piston mostly out, you have to push on the piston until it is close to the motor. Always makes me kind of nervous.

Kinda sounds like a plugged fuel filter or problem with the fuel pump to me. Did the problem happen with low fuel each time? Fuel pumps use fuel in the tank for cooling.

That was my first thought too, but there has been plenty of fuel in the tank and the filter was replaced a couple months ago. The pump was also replaced recently. I'm going to pick up an FSM this week...I've heard you can get them on CD a lot cheaper then getting the book, anyone know where I can find one for my '91?