Had my '15 GLK350 in because It had reached 55k and the B2 due in so many days showed up. Since it's a new-to-me car and I had done all but the trans flush and filter I bit the bullet and went to the dealer. I too had a shutter while accelerating cold. M/B dealer looked everything over and decided that I needed new motor mounts. Hum, I can't help but wonder if they thought they would get a piece of that pie?