shakes from engine when idle, new boxster s
 

This is a new boxster s with 200 miles on it, the problem is:
when the car is parked and idle, I can feel some irregular shakes of the car body, the source seems come from the back of the seats, the engine. (feels like something is rocking the seats) The occurrence is not periodical, but in average it happens every about 5 seconds. This is more severe when the car is just cold started, but still noticeable after temperature reached 175. After running the car on the high way for awhile then put it to idle, this phenomena seems disappear, but will show up again after 30 seconds.
I went to several dealers close by (the dealer I bought the car from is 1 hour away) and tested 3 Boxster S, none of the cars have shakes like that.
Any idea what could be wrong?

I had idle problems too. Check out the pictures and discussion here:


http://986forum.com/forums/performance-technical-chat/5684-98-porsche-boxster-blue-smoke-start.html