Jim:
Pull the stored codes. If you show P0016 and P0017 you have the problem. Mine is a 2006 C230 Sport with 108K. I got the problem. You need to pulll the engine to replace the balance shaft. I fortunetly can do the repair myself. The dealer wants about 5K. For a 5K car this makes no financial sense. So if you can't do the work yourself, its scrap, or part it out on ebay. These M272 engines are problematic.
The intake linkage is also another common failure. In my opinion these engines are over complicated junk. Four overhead cams, mulitvalves per cylinder, variable valve timing, variable intake runners. For what? A wopping 200hp! I have a 1972 chevy pick-up with a straight six that makes 200hp. The Emperor is naked!
Late model Merc's aren't what they used to be. The Emperor is naked!