I purchased a 2006 VW Jetta Tdi last year and it ran fine untill I got 200000K on the odometer. When the car is cold it runs great. I let it warm up a minute or so, drive a hundred meters and sit at the light for a minute, pull away and it runs fine. I get to the next light a half klik away and wait for this light to change. When it turns green I pull away and around 1000 RPMthe car starts to chatter, if I ease off the fuel it seems to get better and when It does acclerate it leaves behind a huge cloud of black smoke. The car only does this for two or three traffic lights and then it runs fine. I took the car to my mechanic after reading what others tried and he took the intake manifold off and cleaned out the soot, he said there was not much soot at all, when I got the car back it ran goog, symptoms were gone. After a week they slowly came back and after two weeks I am right bak to my original problem. Once I had the window down and when the car started to stall the clattering noise from the motor was so loud I thought it was going to blow up but it did not and that noise never came back. Can any one offer any suggestions? Any ideas? I hate the idea of going to the dealer and getting robbed, I know If I go there it will cost about $2000.00 or more and even that might not fix the problem.Thanks for your help.