Engine Vibration at stop

S 320 Inlne 6, for some reason, when in drive or reverse, the car seems to vibrate when stopped.(ex at a stop sign).The enigine runs fine. 700 rpm at idle. 500 when in drive. You feel vibration in the seat and steering wheel.(not major) Car has 90k miles and the engine just had a major tune up. Car drives great, just a little vib at the stop. Are the engine mounts worn?  Thanks T.

The motor mounts for this engine are a common item to fail, I would have them checked along with the transmission mount.  If you want to look at the mounts yourself you can pretty much tell if they're bad or not by seeing if they are collapsed.  There should be about a 1" gap in height between the lower section of the mount and the the top section that bolts onto the block.

Its the motor mounts that need replacement. I had the same problem. Buy cheap OEM parts at http://www.importec.com