AudiForums.com - Car is knocking hard when accelerating, engine "pinging" whats the deal?!!

OK, someone who knows what this could be, as hard as it is to describe, please chime in.
This started a little while ago, now its a lot worse. Car is an 02 A4 1.8tqm, revo BI program with no aftermarket testpipe/fmic or exhaust. Plugs are NGK bkr7e's, about 4k on them, stock airbox, stock filter (hot, no extension) etc. Forge004 valve.

So i let off the clutch in first, without launching the car i hear knocking from the rear at first, knock is very noticeable to me. As i accelerate I hear it knocking faster and car feels like different wheels are getting the power at a different time, also seems like knock changes places, and car isnt as close to powerful, due to these "intervals".It is no wheel bearing, Ive changed many of those. Car shifts gears perfectly, not too easy, not too hard. What the hell could be this? Differential? Tranny god forbid?. Now for the past couple days, especially today driving in about 70degree weather, the car would "ping" HARD when i hit boost in 2nd and there is no way to keep the rpms going, well at least i wouldnt want to try it. Car also stalls sometimes if i release too much boost in 1st from low rpm.(Manifold?).

Clutch on the car is pretty weak, been weak from the beginning. Had the revo for a few months already.
Getting scared to drive it so i dont ruin anythingDrove home without boosting.

Please help me out if youve got an idea