Sometimes (the key word here), I start my Jeep, and the engine races. The RPMs keep climbing, and it won't kick down. Anything I do that normally kicks down a car makes the RPMs climb more. The only thing that resets it is to put it into gear and attempt to drive it for a while (the time it takes is increasing), then turn off the car (it shakes and shutters as it shuts off). When it's running like this, it doesn't want to stop (I have new breaks, it's just the car literally bucks and tries to push through them). Last night, I drove home (I live on a hill 20 minutes from town... by highway) without touching the gas pedal even once. It managed all by itself to do 50mph on the highway. Even on the steep hills, it would slow down, then switch geers, and climb the hill all by itself. This would sound more impressive if you could actually see the hills it was climbing. We have to have 4wd in the winter if we're going to get home. That's how steep it is. Cruise control is not on. It doesn't even work.
The flip side of this is, occasionally, it does the opposite. It caughs, sputters, lurches down the road like I'm dropping the clutch in a manual (it is an automatic), then shuts off at the stop light.
I've taken it in to multiple mechanics multiple times. Wouldn't you know, they can't get it to do it while it's there. It runs like a dream for them. One mechanic (the best in town for Jeeps) narrowed it down to three possible parts, all of which are original but expensive. Because of the year, the diagnosic machines don't tell what's wrong with it (something to do with an early generation computer chip).
Has anyone out there had this problem and actually figured out what it is? I'd like to know if it's something that's cheeper to fix or if it's cheeper to get a new car. I've kind of come to the conclusion that if I can't figure it out, I'll just drive it until it can't go anymore (literally, like dead on the side of the road), then I'll get a new car.
I've owned the car for 8 years as of next month. It started doing this the second year, but it happened so infrequently until last year that it really wasn't a big issue. Then, it went to once a month. Now, it's doing it at least once a week. It's otherwise well maintained, and I try to do preventative maintenance when something's starting to go wrong. This is just one problem that no one's been able to figure out.
This is not my car, but it is what my car looks like: http://images1.americanlisted.com/nlarge/1989_jeep_wagoneer_limited_4wd_14452859.jpg


Does anyone out there have any experience with this problem or any ideas???