2003 protege ES transmission messing up
 

Hello i have a 2003 protege es, 70,000 miles with the sportshift automatic trans.When i put the car in D it just barley moves at all,if i push it over in manual the gears work and shift then i can put it back into drive from manual and it worksd fine until i stop then it has the same thing happen,AAMCO says they dont know whats going on, it reads NO codes. but i probably just need to rebuild the transmission, does this sound right?
it sounds electrical to me, what about a sensor?throttle positioning sensor,or an egr sensor ,another transmission related sensor?
please help thanks all.....