hey dude have you hade the care tuned by any chance??. coz I have the exact problem, I first noticed it when I had my walbro pump instaled, it wasnt any thing like it is now but it was a little noticable. I then took the car to my tuner and had cooler, pipping and injectors instaled, when I picked the car up it felt like a roket ship!! (not power). At a stop, in drive or reverse it shakes and vibrates like any thing. I told them and all they said was it was there before, I couldnt really argue coz it was, but not to the degree it is in now. I asked the question of what it could be but only got the engein mounts answer, could it have any thing to do with the tune???