2002 Saturn L200 Car still vibrating

Have you been able to figure out what is causing this problem yet? I have a 2002 L200 and mine started shaking horribly two weeks ago (it would do this while in idle and get worse if I put it in reverse or drive). Took it to our mechanic who ended up basically replacing the whole suspension system, and it drove fine for a week, then the problem started all over AGAIN. But now it's an intermittent thing - sometimes it shakes when you start it, and other times it starts up just fine. I have NO CLUE what the deal is. The mechanics have not been able to figure it out yet either. If you were ever able to track down the problem please let me know!