Stumpt on trany

I am a little confused on what the problem could be I have a 94 pontiac grand prix 4 door 3100 . When you first start the car it will not move at all but if you let it warm up for about 5 min then it will go and shift fine all day long and you would never be able to tell there was ever a problem with it . please help

The inner input clutch piston seal has gone bad. This is a very common issue. Your options are a rebuild or just drive it.