I think since my 2014 ST was near new, i noticed an occasional condition where the idle would suddenly drop very low, the engine would shake, and then recover to normal idle. The event lasts a few seconds but occurs pretty much during every drive at least once or twice. I really disliked it when i installed an upgraded lower engine mount. It was so annoying i removed the mount and put the stock one back in. Anyone else experience this and determined the cause?