definetly change the tps. I see noisy sensors all the time at work. A new sensor takes care of it 99% of the time.

 

Change the TPS first, then take it to the dealer while you still have powertrain warranty and get the tranny rebuilt! My TPS was bad for a long time with the dealer unable to figure out the problem. The bad TPS caused a lot of lock/unlock of the converter and overdrive unit, which are suspect quality anyway. My converter has been changed twice in 60k miles and tranny rebuilt twice. THEN I fixed the TPS myself.
Better yet - take it to the dealer and tell thaem what it's doing BEFORE you change the TPS. If your dealer is like mine (2 different ones) they won't be able to diagnose the bad TPS and will go straight to the tranny rebuild. Change the TPS after you get it back. Your symptoms sound exactly like mine did. Make sure they replace the converter and valve body if they rebuild it, the original converter has a paper lining that comes apart and gets all in the valve body and tranny.