I was told the same thing. My car does the exact same thing, and I also own a 94 C220. Its done the same throughout my time owning it. I was told by the dealer, that this car doesn't require a long morning warm-up.....instead, just start it up and start driving and the Car..... it will drive rough and higher RPM shift points until it is warmed up... Although if I choose to burn gas that costs me more then its equivlant in Dairy Milk for a nice morning warm up, the car drive's fine. So for you're next cold start, warm it up for a few minutes and see if it makes a difference. If it doesn't, then i'd start to wonder what's wrong with it...