tranny problems on 91 lebaron

hi all i have a 91 lebaron conv. and the tranny wont shift its like its stuck in 2nd gear i had this problem once before i replaced the output speed sensor and it was fine.but now its back i replaced all the sensors in the trannsmission and the tranny computer. any other ideas of what to do im thinking it probally needs new tranny. but it shifted good and then i washed it one day and bang wouldnt shift any ideas would be appreciated thank you. :screwy: