My 2004 Jeep Grand Cherokee Laredo v6 has been in and out of the shop (dealer) for over a month with the same problem. Each time I bring it in they diagnose/fix something else and it comes back with the problem developing again. They are stumped - and I'm not sure what to do. The car has 85,000 miles.
Symptoms: at around 65 mph (or 2000 rpm) I feel the car hesitate a little, and the rpm needle moves a bit weird. Over time (and multiple service visits) this started happening at lower and lower speeds (like 40 or 45, eventually). One time i was on the highway and it hesitated so much it stopped running (check engine light appeared), and I had it towed to the dealer (they paid the towing).
Here are the things the dealer tested, diagnosed and replaced, over this time (in chronological order):
1. Engine misfire - replace spark plugs and 02 sensor
2. Fuel induction cleanup service - cleaned fuel rail, injectors, intake system & throttle body
3. Found a short in the ignition coil - replaced coil, and fuel filter
4. Replaced throttle position sensor
5. Replaced PC module (main computer for engine)
Here is some older regular service history too (in case it's helpful at all to know): Ignition tune-up, replaced brakes, add coolants, replace shocks, replace transmission fluid & filter, replace front pinion seal and flush brake fluids.
Anyway the car is still hesitating at around 60 mph. Although it seems less severe and less frequent I'm scared to keep driving it and I don't know what to do. The dealer once even sent the car to an independent mechanic (he's the one who replaced the PC module) and hasn't been charging me any more for service.
Help!?

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