I have been experiencing Very hard shifts from Park into Reverse for the last month or so. It sounds like the rear end of the car should be lying on the ground. Put it back into park and it will go into reverse as smooth as silk. Today, I pressed the gas pedal to the floor, and - this happened more than once - the tranny shifted down a gear, the check engine light came on, and the car lost all it's power until I took my foot off the gas pedal. After that, it ran and downshifted fine. Anybody have a clue what's going on? This tranny is less than a year old.