weird problem... i think it's the rear?
 

i noticed recently when i give the car like 1/2 throttle from a stop it shifts to 2nd and jerks hard and the whole car jerks, doesnt feel like the tranny feels like its more from the rear of the car. if i give it average throttle it wont clunk or jerk and if i give it full throttle its just shifts hard like normal. It feels like something is gonna break. I also noticed recently while driving around 20-30mph with just a little load on it (enough to keep it at speed, hardly any) that there is a humming/whining noise comming from the right rear when i let off the gas is goes away but just barely touch it again it comes back. could these 2 be related. Im pretty sure the tranny is fine. Any ideas to either of these? car is a 98 a4 ta with 64k miles. thanks guys for all your help.

Check the U joints, rear wheel bearing(s), and service the rear end. It will give you a chance to look at the gears and bearings inside. Clean off the magnetic part of the rear cover, and take note of the slag that's stuck to it. Use fresh grease, and the additive.