94 cherokee, 6 cyl, auto transmission. Problem: suddenly shifts up and down through gears, including hesitation. Had a full engine tune-up, replaced spark-plug wiring and had fuel injector gone through. It runs fine for a day or so and then the problem begins again. We’re glad to do the above work, but a shot-gun approach is costly. Any experience with this or ideas?
More details please. On a level road and constant speed, does it run up and down thru gears? At any speed or only at certain speeds? Or only when accelerating? Or on a hill? How long does this “running up and down gears” continue? How many miles on the car? Have you changed/checked the transmission fluid?
The jeep runs up and down thru gears on level roads (freeway), hilly roads, and at all speeds once it starts manifesting the problem, including just slowing for local traffic. It’s then continuous and the car seems to hesitate or stutter while this is happening. I wondered whether the latter is while cycling thru neutral. 178,000 miles and it’s been scrupulously serviced according to mfr’s recommendations. Transmission fluid was the first thing checked. It was up to the mark and very clean (not driven much since last service). The only question I can’t answer is “only when accelerating.” The problem occurs when slowing in traffic too, so I would say not just when accelerating, but not with certainty. After comprehensive tuneup, car was driven about 40 miles (up and down hills from 40 to 60 mph) with no problem then parked for several days. Problem showed up again after driving about 15-20 miles. I hope this answers your questions and we appreciate your taking the time to consider this. We’re an older couple and depend on this car in winter in the mountains.
An addendum by questioner: mechanics have put an analyzer on the Jeep and it checks out perfectly. They’ve driven the car for a day and can’t replicate the problem but both previously experienced it when doing test drives prior to the tune-up and fuel injection work.