Same issue with mine. New plugs helped for about a week. Engine light comes on and off. Starts missing bad if I get into it. Let the car sit for an hour or so off it fixes itself. Not sure what to do.I have a 200 that has 68,000 miles. Check engine light came on. Showing Code P0301 - Cylinder 1 misfire. It is at the dealership right now. They say there is a problem with a lifter on the right side of the engine and both cam shafts. Has anyone else had this problem? They are checking to see if it is covered under my extended warranty. I have had the car for 5 years and bought it used from a dealership. $4200 if it is not under warranty.