My 1994 Pontiac grand am 3.1 has to warm up before it can move in any forward or reverse gear and I already tried changing fluid and filter.
First make sure your transmission fluid is full with the engine running and the car in park on flat level surface. If the fluid is not full, fill it , drive it and check it again.
If the fluid is full and burnt looking (should be bright reddish/pink) then you are looking at need a rebuild or replacement.
If the fluid is full and was not burnt looking before you changed it, you will need to have the shift solenoids replaced.