1FASTZ28

I have an A4 Camaro Z28. After being completely stoped and then start to drive again it takes a few seconds to engage. When I accelerate I feel two hard jerks when the car is shifting from 1st to 2nd and 2nd to 3rd. My fluid is dirty and needs to be changed, but would this cause the problems I am experiencing, or is there something else wrong with my tranny. IDK if this is due to the transmission, but when accelerating I also hear a whistleing sound coming from the rear of the car.