What's wrong with my transmission??????
 

I feel a strong vibration coming from the transmission after driving it hard and even sometimes during normal driving. I flushed the tranny and still have the same problem even though it happens a lot less. The car also doesn't move right away after putting it in drive from park or reverse. I'd appreciate any tips or advise.

A flush is not going to fix a vibration. Bad mounts, exhaust rubbing, pinion angle, bad u joints and so on would be more likly the issue.