Idle Problem

[mrbill3]

I have an 89 Cherokee Larado, 4.0L, Automatic, 4X4. I just went on a 200 mile eachway trip. After about an hour of driving at highway speed (65 to 75 mph) the idle speed increases to about 1300 rpm in gear and 3000 in neutral. The only way to get it to stop is to shut the motor off for about 2 minutes and the it runs fine again for about 10 minutes. It idles real fast once in a while when I start it in the morning or after it has been sitting for a time. Anyone have a suggestion?

[rksnc]

There has been a problem with some like that. The problem is in the IAC & TPS. They are wire up together in the same harness. It is moisture that causes this. I was able to clean my plug-in apply grease to the connections and mine hasn't acted up for a long time now. About the only time mine does it is if I wash the engine off.

[mrbill3]

Originally Posted by mrbill3

I have an 89 Cherokee Larado, 4.0L, Automatic, 4X4. I just went on a 200 mile eachway trip. After about an hour of driving at highway speed (65 to 75 mph) the idle speed increases to about 1300 rpm in gear and 3000 in neutral. The only way to get it to stop is to shut the motor off for about 2 minutes and the it runs fine again for about 10 minutes. It idles real fast once in a while when I start it in the morning or after it has been sitting for a time. Anyone have a suggestion?

Update- I changed the IAC and the O2 sensor and then went on a 700 mile trip. No more problems.