Idle Air Controller giving me fits

A couple months ago I had a problem with my '99 XJ starting. It would crank up, and then die immediately (no idle). I had no idea what the problem was, so I took it in. The guys there were cool, told me it was just some buildup in the IAC motor, cleaned it out and let me know that I would probably need to replace the IAC eventually.

The Jeep ran fine for a couple weeks until I ran into the same problem again. Cool, I figured this was coming, no biggie. Bought a new IAC from autozone, put it in, voila the Jeep starts fine.

Now here we are however, another couple weeks later, and again I'm getting the same exact problem. Now, when I replaced the IAC, I didn't clean out any carbon buildup. Could this be happening because I didn't clean it out when I replaced the IAC, or could the IAC I put in be bad? I don't want to have to clean this thing out every 2 weeks to keep the Jeep running...

Further, if I do need to clean it out, I'm still not exactly sure how. I've asked a couple times here and the answers were kind of vague. I have some carb cleaner, but on the directions for using it it says to remove the air duct from the throttle body (that's that giant black 4" thick tube on the top of the engine in the XJ's, right?) yet on here it sounds like people have been talking about cleaning the little joint that the front of the IAC goes into, the very small (in diameter) 90 degree right angle. Which is it?

Thanks in advance, I'd really like to get this worked out once and for all as it's now been an ongoing thing for over a month.

I would think if it were cleaned a month ago , it should be alright , and you have a faulty part, wouldn't be the first time. Does it run alright if you hold the gas pedal down a little?

I would think if it were cleaned a month ago , it should be alright , and you have a faulty part, wouldn't be the first time. Does it run alright if you hold the gas pedal down a little?

Yes if I hold the ignition turned and press the gas pedal down it revs up fine, as soon as I let off the gas it dies.

If you still have the receipt I would take the old part back, electrical parts are not returnable but they still do have a warranty and they should give you another one. The next time you clean the iac passages, I would remove the throttle body all together and clean it good, make sure you get a new throttle body gasket before you take it off, I had a hard time finding one and had to make one from gasket paper.

I agree with 89ltd. The only thing I would add is to check the wiring for the IAC to be sure it is working properly.

This only gets worse I'm afraid.

Sooooooo I went ahead and got some throttle body cleaner and cleaned off the exterior throttle body plate. There was a fair amount of carbon buildup on there, got it shining now. Then I took out the IAC sensor and sprayed some carb cleaner into the passageway between it and the throttle body. Cranked her up and she started, drove the Jeep around a bit, tried starting it a few more times and it worked each time. Everything appeared well.

Then, this morning when I went to start it up...disaster. It's not even turning over anymore when I turn the key. It just tries to start up but never turns over, like a constant loud 'clicking' I guess you could call it.

Did I just shoot myself in the foot here? Not sure what I could've done wrong the only thing I really took out was the IAC sensor and I'm positive I put that back properly...

Well, this sounds like your battery is dead (or nearly so).

Check your battery connections. Jump start it with another car.

if it doent turn over when you "jump it" it could be a starter selenoid

I have an issue where if the jeep sits about an hour to an hour and a half on the 1st startup it acts like its barely firing on a few cylinders then dies. Hit the starter again it starts normally with a lil rev like normal. WOuld this cause this? Or am I looking at something electrical? PLugs, wires, cap & rotor are all new. The strange thing is it only does it if its sits about an hour and a half-2 hrs, longer it starts fine, shorter it starts fine. Starts fine cold too.

Thanks,
Jeff