I have an RS4 2, after months of not using it, i finally decided to start it today. It started after a few pulls on the stock engine and the wheels just kept turning and the car was running without even pulling the trigger yet. After a half of the tank, the engine was kinda smokin'. WHAT HAPPENED THERE? WHAT DO I DO?

well there could be alot of things wrong try these

1.adjust your trim make shure the carb is sitting about 1mm open at no throttle input

2. adjust your needle settings right: lean left:rich

3.did you use after run oil? if you didnt you could have rust/gumy stuff in your sleeve and piston if you didnt you might have to replace them (this is also a good time to upgrade the engine)

4.clutch shoes are burning up - change them

5. or it could just be water getting on the hot parts and vaporizing off

Jento261 has his points.
Additionally, it sounds to me that you're runnng too lean on your low speed needle setting, which causes a fast idle and leads to smoking on your engine.
Play around with your needle settings on idle, both the idle and low speed needle. As in the previous post,
1) Adjust the throttle trim all the way left to "close" the carb;
2) Adjust the idle needle so that the carb opening is about 1mm at no throttle input. Note: Turn left to lean and right to richen.
3) Adjust the hi speed needle starting at around 2 1/2 turns out.
4) Adjust the low speed needle starting at around 2 turns out. Too lean at low speed needle setting will rev up the rpm and thus the fast idle.
Run rich!!

...

I thought the low speed screw was supposed to be 3 1/2 to 4 turns out?

i think that there is too much gas goin in and it leaked over th hot engine. not good. anyway, about having to turn the needle 3.5-4 turns the book says 3. however, you get your car to start and adjust it until it runs good and strong.