Hey, I'm new here I have an 2002 jeep grand cherokee Laredo 4.0l with a few bolt ons I have a new 62mm throttle body, 4 hole fuel injectors, and
k&n cold air intake. Recently after the jeep warms up.and the idle air control valve closes and the jeep idles down I can give it gas and the iac opens back up and the jeep revs up with very little gas. I replaced both the iac ,throttle position sensor, and crank sensor. When I reset the battery the jeep runs fine for a week or less and than acts up again. Also runs back to normal after unplugging the iac and plugging it back in.. I'm stumped any help would be awesome. Thank you

 

I have had bad IAC right out of the box twice, Belden brand both, I was suprised, and one faulty TPS, my local Napa did honour the exchange. I've had the intermittent idle problem also over a few days. On the XJ it took 3rd IAC and second TPS over three month period to correct fully, good for couple years now.
Doorman and Standard brands components have worked for me without problems and they are considered pretty basic aftermarket brands.
My local Chrysler dealer often will sell a Doorman component, not a Chrysler branded component, so OEM parts are not always available.
Check Cruisers tips, many apply equally to my XJ, ZJ, and WJ all with 4.0L.
Confirm your grounds are good, it's not just an XJ problem, all vehicles can benefit from confirmed grounds.

 

PS: Since you've got it exposed, insure the throttle body is clean. A little decarb or brake clean spray and your brother in law's tooth brush will work!

 

Haha thank you for your response.I hope it's a bad iac right out of the box I was thinking a bad pcm because it will run good after I reset it than slowly act up again. I'll research how to test the iac. Thank u again for your time

 

How did you test your iac valve to find it was bad?

 

JMHO, "Change it with Mopar, change it ONCE!"

 

I went back to autozone and exchanged it for another new one. I don't think the iac value is the problem. I ohm all three iac values and they all read 52. Here is another way to explain what's happening everytime i give it Gas the iac opens up full and let's alot of air in, causing the idle and power to increase.when I let off the Gas it stays reved up till the iac closes. When I unplug the battery to reset the computer it'll run ok for a few days. Found unplugging the iac for a short time and plugging it back in would also bring it back to normal for a bit Any help would be amazing can't really afford a shop to look at it.