I have a 1998 SL2 with Automatic transmission. When the car is cold, the shifter can not be moved out of park...but after about 2 to 5 minutes with the engine running (warming up) the shifter moves fine and easily engages in the gear settings. No other problems or noises. What's up with it? How do I fix it? Can it be done at home (I am a fairly competent mechanic with tools)?