shift lever (automatic)

For about a month or so, my 1998 Saturn SL2 won't shift out of park untill my car is warmed up. It's an automatic transmission, the shift lever won't move from park untill the car is warm, one person said it is the valve body, but upon further inspection from my Haynes Repair Manual there is no valve body. I have removed the center console to peak at the shifter, nothing seems wrong, but a hydralic arm attached to the lever doesn't seem to extend all the way untill the car has reached normal temp. speeds. Please help i'm running out of options. THANKS