Rear Kicks When Given Medium-High Grade Acceleration

[FormulaFiend]

I can't quite figure it out. Was on the interstate the other night cruisin with one of my buds and someone did a fly by so I gave it some get up and go to catch up. When I was at wot, I could feel a kick in the rear. Not throwing any codes or anything, but now anytime I give it any normal or high grade of acceleration I feel this horrible kick in the rear. It also does it in between shifts. I own a 99 Trans Am A4. Can't quite figure it out. Wanted to get opinions before I take it into a dealership and get raped. If it's something I can fix myself then I'd rather that be the case. Any ideas or similar situations? Thanks for your time. It is much appreciated.

[0rion]

can you give a better description of "kick". Sounds like a possible tranny mount to me but that's pretty much a guess at this point. Does it definitely come from the rear of the car or is it more towards the middle? Does kick= bang? It could be a whole list of stuff so try to be as detailed and accurate as possible with your description.