It's hard to tell what sort of vibration you have from your description, bu
t we can generally put idle vibrations in two categories: abnormally rough
running engine or improper vibration isolation.
All engines have some amount of vibration, but this is relatively low for t
he 2.7. For excessive engine vibration, you should consider misfire and ab
normally low idle as potential causes. For improper isolation, consider a
weak or broken engine/transmission mount.