Hey guys,

So today while out wheeling my 88 Cherokee started idling very low/rough. It was about 2 hours into the trip and slowly got worse and worse. It got to the point that if I wasn't on the gas it would stall out while in gear (Auto Trans). I had to shift it in to neutral when stopped then pull it down to 1st and get on the gas right away to just keep the thing from stalling...

At first I was suspecting engine idle problems until I realized that putting it in neutral allowed it to idle normally and putting it in gear caused it to idle rough and stall. If it matters I was in Low 4 for pretty much the entire time.

I left the jeep in 1st gear and drove back to the road slowly. After driving with it only in 1st for about 20 min, It was back to normal. No idling issues at all. I put it back in drive and had no further problems...

It seems to me that maybe the transmission overheated?? I don't have a gauge so no sure way to tell. Is it possible that leaving it in first gear allowed the Trans to cool enough and return to normal?? The jeep didn't seem to be doing to much shifting to begin with. Also seems odd that I could shift it perfectly fine manually.

Any help on the diagnosis would be appreciated! Thanks!

 

While it's possible you have a trans problem, I suspect you have a misfire or bad IACV. A misfire caused by something like a vacuum leak will show up worse when in gear because there is load on the engine. In neutral there is very little load on the engine and symptoms might not appear. Look for any broken/cracked vacuum lines, especially the little elbow going from the MAP sensor to the throttle body.

 

I will check out what you suggested once it stops pouring outside.

Now would this problem be intermediate though? Once the car was allowed to be driven slowly for awhile the problem completely went away and hasn't returned yet.