Engine Knocking Noise problems of the 2006 Volkswagen Rabbit

This is my second complaint. My 06 vw Rabbit has been stalling since approx. The second month that I had it (bought 06/06). In August 08 after continually complaining about this issue my car first started to sputter "like the timing was off" while driving (not the first time for sputtering but it usually does it when idle, not driving). I took the car into dealership and they could find nothing wrong even though the car sputtered 3 times on my way back home. The very next morning the car started to smoke very bad, smell like gasoline, and a light was flashing on the dashboard. I burned a 1/4 tank of gas driving approx 10 miles to dealership. The dealership had the car for two+ weeks and has since replaced the 02 sensor, fuel injectors, etc. However approx 2+ weeks after getting the car back it stalled again. The car is also occasionally making a strange knocking noise behind the steering wheel (which has also been an ongoing problem) and occasionally the tailpipe is "backfiring" not like a loud boom but like a release of air (which had only happened twice before and now happens more often). I can't stress enough how bad my nerves have become while sitting in traffic which is what I do at least twice a day. The car mostly stalls when the car is idle (I. E. Sitting at lights, sitting in traffic, parking spaces). Because the issue is sporadic I cannot get anyone to take this matter seriously because I have no way to prove it since the codes clear after the car is restarted and vw does not have a black box to record the incidents. I have found sites with people having the same problems and getting the same response from the dealerships. I think this unsolved mystery with the stalling is making the wear and tear on my engine worse because my car no longer runs the same and problems just keep getting worse. I don't want to wait for the warranty to run out before more serious problems show themselves.