Automatic transmission problems

The car does not shift correctly. I can get it to go into reverse most of the time. However it rarely wants to go into drive. When I shift into drive the engine will just rev. It does go into drive then I have to push the gas very easily because if I push too fast then the engine revs. If you can get the car to go forward it does sound like it is shifting out of first gear. I drained the transmission fluid out and put in new fluid. While the front end of the car was up in the air. I started the car and shifted the gears. And there was no delay for the wheels moving. I pressed on the gas and the wheel sped up like they should. However the original problems still occurs when the car is on all four wheels. To me it does not make sense that it would work in the air but then not work on the ground.