My 2000 s40 vibrates really hard when idling but is smooth when I am on the gas. Pretty bad vibration, the whole dash looks like a blur. Is that a motor mount? The dealer I bought it from said that he had just changed the plugs and wires and since it had been so long since they had been done previously it needed to be run for a while so the carbon build-up would go away therfore making the vibration go away. Is he completely full of it or is the motor mount bad?

 

Why don't you open your hood and look at the motor mount.

 

Motor Mounts.