Judder Through Cabin Of Tdi 130 Sport

Hi

can anybody help before i go mad

I have an A4 1.9 TDI Sport 2001 (B6), The car is fine when cold but as soon as normal running temp is acheived and the car is stationary the car begins to vibrate and judder in the cabin almost like there was a missfire with the engine however there is no fluctuation of the rev counter and the engine seems fine.

I have had the car into three garages including Audi and they cant find the fault. I have had 2 engine mounts replaced, Fuel filter replaced and the whole engine including the injectors checked and everything is fine.

Appart from this problem when stationary the car runs perfectly and is very fast therefore i doubt it is a problem with the engine.

A friend told me of some sort of deisel pre heat engine which is attached to or is part of the engine and he suggested this however i have never heard of this before

Can anyone out there help.

Thanks