while im driving my 06 a4 the rpms will go up and down but if i step on the throttle harder or let off it quits! any ideas? also can anyone tell me how to disable the seat belt buzzer?

 

have you checked your mass air flow? i know with the B5's if you unplug it and the car runs better (at idle) then it is the maf. not sure on how to check yours but it could be that. i did have a similar issue and just replaced mine.