It's likely to be caused by bad motor mounts if the engine itself isn't misfiring. All of these diesels vibrate, but when the mounts go bad they transmit the vibration to the car so you notice it more. Have the mounts checked, and if they are collapsed, as I suspect they are, have them replaced. It is not a hard or expensive job and the results are dramatic.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz