1990 7mgte with only 120K miles on auto
 

so i am having transmission problems especially when i am crusing down the highway.. when i wromp on the gas pedal it hesitates and makes like a jerking sound the rpms barely go up and the mph barely moves. i don't kno if its a highspeed clutch problem or if its a bad sensor the transmission fluid has been recently changed..

Welcome to the forums. It's hard to diagnose something like this without actually seeing/hearing the car, perhaps you could post a video from a standing start accelerating moderately to say 45mph & then flooring it (going for kickdown)?

Not sure what you mean by a jerking sound either but from the fact you say the rpm's hardly rise I'd suspect a misfire, meaning it's more likely an engine running fault than a gearbox issue. Generally autobox problems seem to fall into one of two categories, slipping/loss of drive (symptoms, revs rise out of proportion to speed & don't drop when the box changes up. like a slipping clutch on a manual basically, or just no drive at all). The other usual autobox fault is jerky/sudden changes which can be caused by sticky valves or dirty fluid.

Like I say it's hard to diagnose without a video, but I doubt you have a gearbox problem from this post.

Cheers, Dan.