Hi I am a newbie to this forum but I have a problem with my 98 A3. Due to my heavy right foot and clearly poor judgement I managed to run the car out of petrol. Managed to get some more petrol and ran through half a tank when an intermittant problem has started occuring. Sometimes the at idle the revs drop below 800 then come back again. When i accelerate the car feels like someone is giving the car power then taking it away. As you get faster this shuddering still exists but is not that noticeably unless you drop into third and put the pedal down. After a while it will clear and everything is fine. It doesn't happen all the time which is more annoying. Somoeone mentioned that it could be my DV (divertor valve) but I have no idea what that is. Can anyone help??? I have tried putting the injector cleaner in the petrol and it seemed to help but it could just be my imagination.