Acclaim tranny issue

I've a 91 Acclaim with 3.0L and 4 speed tranny...Won't shift into over drive and after 5-10 miles won't out of second. I've changed both the input and output speed sensors, Trans relay and changed the fluid and filter. I had my mechanic change the solenoid out with a good one with no success. Took it to another mechanic who had an old scanner and it said the engine wasn't getting up to operating temp...bad thermostat and I changed it. Unhooked the battery and the tcm and still nothing...Shifts fine 1-2-3, shutters three time trying to shift into overdrive then again after about 5-10 mile goes in limp mode. Any help out there??????