If your vehicle is idling roughly there is something else wrong with your car. Drygas is masking the problem but it isn't the solution. Either you have a dirty throttle body that needs to be cleaned with carb cleaner, or you could have a poor injector spray pattern (usually caused by using discount gasoline). Is the check engine light on? If so you should get it scanned at your local parts store and report the codes back here. Also look for any looses or broken vacuum lines. If after you clean the inside of the throttle body that doesn't fix your concern you should look into running a fuel injection service and get the vehicle scanned by a VW specialty repair facility.