I have a 2001 Sunfire 2.2L with 4 speed auto tranny.

Out of the blue, my tranny started acting up really badly.
I think I hit a pretty big pothole on my way to the gym.

Leaving the gym, i noticed my tranny was slipping pretty bad, especially when taking off at a light.

Then when I parked it again, I tried to get it out of my driveway, but reverse would not work at all. It would rev, and sometimes it would seem to engage for like a split second, making the loud clunking sounds from underneath the car.

I tried puttin the car on neutral and back it out pushing the car, but its as if it was in gear. So i would shake it back and fourth till i heard sort of a clunking noise, then the car would move back about 3-4 feet before the wheels would lock up again.

Do you guys have any ideas what is going on? It seems to drive fine forward, with a little slipping. I have added some Dextron III, doesnt seem to do much.