i have the same problem when waitin at like a light of something.. car shakes a lil bit... when in N or park it doesnt do it anymore.. a while ago some1 told me to get a part checked for cracks the Tensioner Pulley ... go here
http://contour.org/forums/Forum3/HTML/000846.html he explains hope it helps im thinking of doing this also..
-afr0
ill let ya know if i try it before you do ..its doesnt bother me that much cuz i just turn the bass up a lil bit and i dont even notice
