Transmission won't shift into drive after sitting overnight

Hello,

The transmission in my Grand Prix will not shift into drive after sitting overnight. It will finally go into drive after the engine has been running for a minute or two. I'm not sure if revving the engine or changing gears makes a difference. The transmission shifts fine while driving and will even shift into drive if the car has only been sitting for a few hours.

I checked the fluid and it was a little low, but filling it did not make a difference. Does anyone have any ideas as to what could be causing the problem? Will it be an easy fix or an expensive rebuild?

TIA,
Brandon

will it go in first, second, third manually on cold start?

If I put the stick on 1, 2, 3, R, or D I get the same results.

It also only happens when the car is parked with the front end on the low portion of a slope.