94 XJ stalls when cold, I have changed parts.

I need some help please. My XJ is driving me crazy again. Its a 1994 XJ, 4.0L, 4wd, automatic AW4, with 177K miles. When Jeep is cold and gets started up after sitting for several hours idles fine runs fine then maybe a mile later if at a stop light it just stalls. 95 percent of time starts right back up and no other issues. Some times takes a few minutes to get it going then fine again.

I just put a new high flow cat, o2 sensor (jeep dealership part not part house), TB position sensor (off a good TB), ECU coolent temp sensor in thermostat (jeep dealership part). I have changed all of these parts in the last 1000 miles and still have stalling issues when it sits for a few hours. I am running out of my expertise of ideas. Most times don't care as Jeep sits a lot but due to primary car repairs my XJ has had to be brought back into full time driver the next couple of weeks.

Thank you

Tonight out of random luck a new symptom which it has never done before. In idle, if you just tap the gas idle jumps from 800 rpms to like 1500 for like 3-5 seconds then goes back down to 800.

Check the brake booster for a vacuum leak,
also the check valve. With the engine idleing,
put your head under the dash and listen for
a leak while pressing the brake pedal with
your hand.

Might be a sticky IAC. I periodically squirt some spray oil into the IAC opening with the motor running (at least twice a year). I work the throttle a little while I'm doing it. It seems to flush out the grit and semi solids that can jam up the IAC piston.

This is a lot easier than having to remove and clean it and seems to get the job done just fine. I almost lost the red spray nozzle extension down the TB once, I now super glue the extension on the nozzle.

I've also noticed a sticky IAC can be the first indication of a battery or charging problem. I've had my IAC start sticking and acting up way before (weeks) I ever noticed I had a charging system or battery issue. The IAC seems to be voltage sensitive (for whatever reason) I've noticed this on multiple XJ's over decades (Renix and OBD's). After about the fifth or sixth time you see the same circumstances and outcomes, you tend to notice a trend.lol.

I'd avoid using strong solvents, spray oil seems to work well, just enough to get it functioning without washing all the lubrication out. The IAC comes new with a light grease on the gear drive, probably not a good idea to wash that off.

Th IAC controls your idle (or the amount of air the motor gets) when you release the gas pedal and the throttle plate closes in the TB. If it stalls when you release the gas pedal or even if the motor seems to stick at a higher than normal RPM's for a few seconds whne you relese the pedal, it is likely to be the IAC. TPS and vacuum leaks can also mess with your idle. Though major vacuum leaks seem to be fairly consistent and more often present as a high idle and not stalling.

Thank you guys! I never associated the IAC on the TB as it controls the idle, I always thought the TB position sensor did that and thought the IAC was part of the cruise control system lol . I will play with it and clean it later on, thanks again!

I can confirm the IAC/low battery- recently forgot my ignition on- drained battery. Charged it, but took it off the charger prematurely- the battery had enough to turn over but would not start. Held throttle open a little and it would start. Let off throttle and it would die. Drove it a little and everything went back to normal. If a sticky IAC would react similarly and it sounds like it would- this is definitely an area to look at as suggested.