What do you mean you "lost" your overdrive. If you are in OD at 45mph and you hit 50mph it will jump out of OD? Check to make sure the blue wire that attaches to the wiring harness at the fire wall is connected to the correct wire. That is your TLC. Torque Limiting Calibration. It is designed to back the power off just before shifting and lock up. I have some transmission upgrades and disconnected mine.