[JhwShark]

Vacuum can be an issue for low rpm vibrations, though would usually be noticed in neutral...How many miles are on the car?? Is the vibration an engine misfire? Could be fouled spark plugs, fouled fuel injector/s, O2 sensors?? How is the gas mileage and what were the results of the last smog test HC, CO, NO?? Bad or degraded motor mounts could cause vibration but an '05, my '93 (250,000 miles) has original mounts. I do not know this model/engine/drive-train very well...

Has anyone pulled engine codes to trouble shoot? Did the dealer even do this before they said the stuff the said?? They may have bypassed a diagnostic step to Deal you.

Dealers...deal...sometimes they fix (though they do not know the older rigs). In the future ask the board for some suggestions before the Dealer.
Jon

added: maybe a drive coupling to the rear drive...center bearing or Guibo couple (if this car has them)