Steering wheel vibration while stopped is common in 4-cylinder engines.

Dear Car Talk | Sep 01, 2004
Dear Tom and Ray:
I have a 2000 Mitsubishi Galant with only 7,000 miles on it. I have recently noticed that the steering wheel vibrates even when the car is sitting at a stoplight. I took it to the dealer, and he said the vibration is normal. Any thoughts? -- Bob
RAY: It could be normal, Bob. This is not an uncommon problem. And it's not just Galants. We see this on four-cylinder Toyota Camrys, too.
TOM: I'm assuming you have the four-cylinder engine. A lot of four-cylinder engines vibrate in Drive when you're stopped at a light. The reason is that by design, it's not as smooth as a six- or eight-cylinder engine.
RAY: Four-cylinder engines vibrate because they produce fewer explosions per turn of the engine's crankshaft. So, with the explosions spaced farther apart, you tend to be aware of the spaces between them.
TOM: Think about a lawn mower with a one-cylinder engine. Think about how much THAT vibrates.
RAY: I'm assuming that the vibration is only noticeable when the car is under load (when it's in gear) and the engine is running at idle speed. Once you speed up, I'm sure the vibration disappears.
TOM: My suggestion would be to ask the dealer if he has a used 2000 Galant on the lot that he can let you drive. If it vibrates the same way, then you might be out of luck. But if it's better than yours, you can then ask your dealer to do something.
RAY: What he can do is check or even replace your motor mounts. The motor mounts hold the engine in place, and they're supposed to absorb some of the vibration. One of your motor mounts might be broken or cracked.
TOM: He can also try adjusting your curb idle speed just a bit. Sometimes by moving the idle speed just 50 rpm in either direction, you can get the vibration to go away.
RAY: And if none of that works, try to think of it as your very own "magic fingers" machine. You won't have to check into those sleazy motels with a roll of quarters anymore. You and the missus can just go out to the driveway with a bottle of champagne and sit in the Galant.