Check the lockout cable for complete actuation. It's the button you have to press to move the shifter. Most likely the cable has stretched or slipped and isn't pulling the lever enough to allow it to move into Park.
October, 25, 2012 AT 2:44 PM
There is no cable. If you shut off ignition it will shift into park. The reverse lockout solinoid remains out at times
October, 25, 2012 AT 2:51 PM
Ok. Then the solenoid isn't being energized or de-energized correctly. That means the switch that had to be activated to shift into Park is faulty intermittently. And will only get worse.