Vibrations

My 2003 Highlander recently began vibrating (in drive, full stop). It vibrates enough to feel it in the steering wheel and seat; even vibrates loose stuff in the car. Dealer says it's normal (which it isn't because it just started) and was probably due to having the heater on (which is a bunch of horse hockey because I turned the heater off and it still vibrated). Anyone have any suggestions? Other than, of course, using it as a reactive target?

It might have been 2 years since this post but my '03 is currently having this problem as well... but the problem only happens when i am going 60-70 mph... other wise it is normal? What gives?!?! I did get 2 new tires and that stopped the vibrations described above, but now i have this new problem?!
Any one else getting the same problems?!