Lost Over-drive???? All of a sudden I just noticed that my t65 tranny is not shifting into overdrive. It acts like when I put it in 3rd or drive, it goes through all 4 gears just as smooth as ever, however, does not shift for the 5th time regardless of speed. Symptom, you can tell when you leave shifter in 3rd gear, it goes through all 4 gears just as smooth as ever, and you can tell your still in 4th by letting off the gas going down a hill and you can feel 4th is slowing down car and tack slowly slows down. However, if you put car in drive and let off gas going down hill, the tack will drop to 900 or so RPM, and the tranny does not slow car at all. Just as if you had put in neutral. I have replaced filter/fluid, and installed a new throttle position sensor to no avail. HELP! should I replace the PCM (Powertrain Control Module)?