So I've been battling with my starting/stalling problem for months now. The issue is most of the time when I try and start it, I need to push the gas pedal all the way down for a few seconds in order to get her to start. Then shifting from park to reverse the idle becomes rough dropping to 200 rpms, and almost stalling, same thing from neutral to drive. Then the jeep drives okay besides high idling, and if I press the gas to quickly or hard it will stall. So with that said, a month ago I replaced the TPS, no luck. Also cleaned out the throttle body that day too. Then last week I replaced the IAC, First start needed pedal pushed. Then a miracle came and the jeep started with no gas pedal pushed, idled at 800 RPMS, would start off my viper remote start first try, this lasted about 3 days, and then the same issues before the new IAC came back. So I returned the part got a new one, and I'm back at square one. I noticed on my way to school today that after driving for a little my temperature gauge came to life, while it stayed on the jeep would idle at 800 RPMS, and ran great. Only thing is the temp gauge goes on and off every other minute. So I'm wondering if the IAC, AND TEMP gauge are connected. Since it seems to work fine with the temp gauge on, while when it's off , idles rough.

 

From my limited knowledge if the temp sensor is bad, the engine gets bad info and doesn't realize the engine temperature is not cold thus creating starting problems. Hopefully someone more experienced can chime in and correct or add to what I said.

 

I would go ahead and replace the coolant temp sensor, it can cause all kinds of starting/rough idle problems and it's relatively cheap. What year is your XJ and how many miles on it?

This could also be a vacuum leak, do you see any brittle or cracked hoses, intake piping, etc.?