I just bought a 93 Sunbird with the 2.0 OHC. The engine idles smooth in park(maybe a slight vibration), but when you put it in Drive it vibrates significantly at idle(shakes the entire dash and interior). The minute you get, even slightly, on the gas, it stops vibrating and is very smooth. It just vibrates bad in idle. ANy thoughts on what could be the culprit?

I changed the 02 sensor, timing belt, serpetine belt, PCV, and all fluids(except tranny), and she runs real good just vibrates in drive at idle. Its gonna annoy the crap out of me!

Nick

my girlfriends precidia does the exact same thing.. im not sure what it is on that........apparently people say its the alternator but im not sure how that can change the problem?

I would guess the mounts, motor/transaxle.
Or some slippy clutch-packs if its an ATX.

I'm starting to think it might be the mounts too....how much movement should there be in the engine when you switch gears?

Minimal, there will always be some, but use judgement on what you would think is too much.
Try to locate the mounts, there are several, and watch them on an individual basis as a helper shifts the in and out of drive, or reverse, whatever suits you best, to see which one is bad, if not all, the car is old, so prolly all need attention, but the failed mount(s) should be obvious.
Hope this helps ya.