For the info, I have a 1998 Cherokee classic with a 4.0 and automatic transmission, also a K&N intake, the manifold is an APN, and a high flow cat and Flowmaster super 44. I did clean my throttle body and GENTLY pulled my IAC to clean it as it was terrible. OK, so before anyone wants to ask if I checked, I already looked through previous threads for about two hours. I replaced my exhaust manifold and I already know I have a leak, down where the manifold meets up to the down pipe, they will not meet up properly. I'm going to have it fixed in a few days. The strange thing is I reset my ECU and now my idle will not level off. I let it run for 20 minutes today and it started as it always does around 900-1000, but after five minutes it would go up to over 2,000 and back down to about 500 almost as if it was going to shut off, then up to 2,000 then back to 500 then back again over and over as if it was trying to find the right balance. I didn't take it down the road, just wanted to see if it would level off.

Does anyone have an idea what is happening or a place to start?

 

Until you fix the vacuum leak its never gonna idle correctly .

 

OK, no vacuum leak, exhaust leak, but that shouldn't affect my idle.

 

I had a similar problem. I replaced the TPS and it idles perfectly

 

Gotcha, well I'll check my TPS, got a cheap voltmeter. How do I do this to make sure it has or has not gone bad?

 

No clue. I just figured it was the tps because only a week before, I bought a cheap Chinese one off eBay and immediately caused problems lol. I got a quality mopar one and it s much better

 

Oooppppsss ....exhaust leak will effect running but don't think it will cause the idle issue.

 

Gently pulled IAC ?

 

When I cleaned the throttle body I pulled off all the sensors so that I could clean it properly. When I pulled the IAC I knew to pull it gently and not too rough. Didn't do a lot of twisting and stuff, just straight out, carefully.

 

When u pulled out the map sensor. Did u carefully pull it out too? And carefully put it back on? The vacuum elbow is very sensitive to tearing or dry cracks. And can cause a lot of problems.

 

I was very careful with all three if them, but I know I still can mess **** up. I'll take a look at them when I can tomorrow. I just want to avoid blowing money on stupid **** when I can just figure this out myself.

Is there a way to adjust the TPS if I might have moved it from the original position when I put it back on?