If your engine seems to vibrate too much or maybe your exhaust header touches the car's pan, then maybe your motor mounts have failed. Or, you don't have the correct ones installed. Its pretty common. Many vendors sell an "OEM" mount that is not the Porsche liquid filled mount. The knock-offs look almost identical, so some ID information might be helpful.

Look for the "P" stamped into the rubber part of the mount. If there is no "P" then don't expect your car to idle and drive as smooth as the original.