Hello, I wanted to ask if you might have any approaches what it could be if the engine is not running completely round. Specifically, this means in my case (V6 Tdi): In the stand everything is fine, as soon as I drive a constant speed then the speedometer always varies a few mm up and down. In certain speed ranges less and in some cases more often (shortly after switching into the 3rd gear it seems to me that the fluctuation is greatest). It is also clear that the engine noise with the speed variation becomes a bit louder and quieter. One small thing I noticed: when accelerating, shortly after switching into the 3rd gear, the speed goes up to about 40 km/h normally, after that it falls short of about 100 revolutions and then goes up again normally. Could it perhaps be a clogged fuel filter or air filter? Or possibly Lambdasonde? Thank you and dear greetings, Pete