Transmission Troubles

My 90 Cherokee has the automatic five speed transmission and I know it is Asian-made, but my first question is which one is it. AW4?
Couple Problems here.....

When the thing is cold it will rev to close to 3000 rpms before shifting out of first and then at random times it will do the same thing.(but not all the time)

The other problem with it is when I let off the gas the whole car jerks backwards-it has done it for a good 40,000 miles so its not that I'm not used to it but I'd still like it fixed. Took it to a transmission shop and they said it might be the front differential.

The only other thing is when I get it up to 55 about 40% of the time it will not know which gear to stay in(and I can never get it to act up when a diagnostic guy is in the car with me)but it slips between 4th and 5th.

Any help would be greatly appreciated.

Think I got this one figgered out- your tps (Throttle position sensor) Had the same problem only I had the shifting problem before the throttle went into warp drive. new switch runs about $60 here- before I sprang to buy new- hit the junkyard and worked fine. Make sure your cruise control is off too, remember hearin somewhere that a short in that circuit could cause the same symptoms

Hey Ironic thanks a lot, replaced the old TPS-runs great. It fixed the jerk-back and made her shift much smoother. I'm gettin better gas mileage because the rpms are lower-its fantastic. Thanks again.