a little stumbling in the morning
 

This morning I started the jeep up and it had a little stumble. It cranked up just fine but if I gave it a little gas while sitting idle it felt like it would stumble a little. It never stalled and after a few minutes it was fine. It did not do this again today but it did worry me a little. Any ideas? I have a new IAC, alternator this weekend, replaced plugs almost 6 months ago. I need an oil change but that shouldnt be the issue. I have noticed it did this before when I let it sit for a day over the weekend without driving it and only on cold weekends.

1. What type of plugs did you install? The 4.0 does NOT like Bosch plugs. Champion copper or NGK will be fine for your 2001

2. The throttle position sensor might be starting to become flaky...........

3. Did you thoroughly clean your throttle body when you replaced your IAC? Very important as a dirty throttle body can lead to the stumbling symptom you mention.

I used the cheap champions

TPS was changed with IAC

I removed the throttle body when I replace the IAC and TPS and cleaned it by hand.

My jeep does the same thing when it has sat for over a day and it's cold.... I just rebuilt the crazy thing and replaced everything including iac spark plugs wires cap rotor injectors and cps.... The only thing I haven't replaced is the map, and mat sensors, and the tps... So it could be one of those three.

Hey Ken, what did you ever find on your stumbling problem?

Mine does this too once in a while in the mornings. I'd say more often than not... but probably reasonably close to 50/50.

It's not bad and goes away after maybe 20 seconds, so it hasn't really concerned me yet.. I just contribute it to the possible need of a tune-up and new injectors/clean injectors.

My cherokee does this and its the vaccuum system. I'd check that.