Hi iv just brought a 1999 A4 Avant with an annoying judder below 2500 rpm. I got the car for a very good price because of this fault and know my way around engines quite well so thought id take a chance on it. Its only done 84k miles with full dealer servcing. Since getting it i have swapped the coils and leads with my other A4, fitted a new Cts and cleaned the Maf with alchohol but still no joy. Also checked fault codes but none showing. Any ideas what to try next? Im thinking plugs maybe but according to the sh they where done 8k miles ago. Are there any flaps or valves on these engines that can stick?