transaxle problems

i have a (96 grand am se)the trans won't shife normally,in order to make it shife,the engine has to be pulling 5g rpms,but then it shifts fine.i have tried putting 2 other trans in and still the same problem.could there be anything else like a bad wire conection,or a speed sen nolonger working on this type of vechicle there are 3 speed sen if anything helps i'm working with a (2.4 twin cam)

is this an automatic or manual? if the transmission lines arent blocked I would say it was an electrical issue. But it is very possible the tranys you put in were bad too. Was the fluid levels correct on the transmissions? A low fluid level will slip like crazy and burn the shit outta your clutches/bands. Good Luck and Welcome to Automotive Forums \,,/