Carsdoki

I have a problem, Audi Allroad 2.5 diesel v6 engine PSG5 pump 2004 year. sometimes the base gas does not go back until 1200 rpm and the engine shakes, when I give gas then the engine shakes up to 2000 rpm. There is no error code. Ignition timing is good. When I test it with VCDS, the timing still raises the revolutions to 1200, you can hear that the timing is changing, but the engine works fine. I can't find the cause of the error. Does anyone have experience with such a case?