Just acquired a 2007 ML 320cdi, with 42 k mileage and FMBSH. When turning the engine off about 50% of the time I get what feels like a ' Shudder ' , not like my E 320 cdi which just stopped without any vibration. Wondering if it is a bad engine mount. Also after using kick down to 4000 revs and then coming off the throttle I get a bit of vibration through the throttle peddle, engine pulls very well and is smooth, other than a fast idle at approx 900 revs it seems fine. Any thoughts?