Hi, I recently changed the clutch on my 200 tdi only to get a vibration at idle about a week later. It turned out to be the gearbox mount, if you look at the mount there should be about a 3/8 clearance.

Try driving the car and then put it in neutral and let the engine idle while you are coasting, then start to brake quite hard and if the vibe goes then chances are thats the problem.

As you brake the engine moves slightly forward and takes the weight off the gearbox mount. A further check to confirm is at tickover put a jack under the lowest part of the transfer box and just lift the box a few mm and if the vibration disapears get a new mount. It seems fitting the clutch with the disturbance ect just finishes the mount off if its already tired.

I have felt this same vibration before last year but that turned out to be a stoned wedged in the mount after a rough time in a dry river bed so I had a clue already.

regards

Dave