Hi everyone was sitting talking to a guy at my local shop, tonight for about 2 hours the engine temp wasnt fully warmed up but had been previous to having the chat.I started the car and just as i was leaving he said that sounds nice give it a rev so i did reved it to about 3500 or so and the cars engine became eratic for a few seconds, like as if it was missing or overfuelling the revs went down to 800 for a second or so then back to 900 to normal, but the car kinda shuddered like as if twas running on a cyclinder less or the waste gate was stuck on the turbo. I drove it then and it was fine and gave it a rev afterwards and its fine just a little worried any body got any idea or experencied this the car is a 2.5tdi 180 bhp quattro a4 b6