Could be a loose or broken motor or trans mount. Try having someone rev the engine with the hood open and see if there is excess movement of the engine. Compare results to another car if you are not too sure. Do you have any problems with the clutch fully disengaging?
Hooters, hooters, yum yum yum, hooters, hooters on a girl thats dumb.
07 2WD Trailblazer SS, LS1 E-fans, 4" FWI, pcmforless tune