I drive a 2001 c240 in Michigan. Just hit 100k. It idled rough for a month, then the cel went on with cylinder 5 misfire. Drove for the rest of the day as it was a sunday, then it ran a lot worse. Dropped it off at mechanics. Monday morning it was cylinder 3 and 5 with random miss code. Replaced the coils and plugs on 3, then replaced coil wires and plugs on 5. Then it missed on 2. Kept driving it, now its missing on 5 only. I used Bosch OEM everything. It will sit over night, cel will go off. NOW IT ONLY MISSES ON 5 AT ABOUT 5500 RPM.

Help please. Can't get it to stop missing.

 

Go to a professional. If coils and plugs were done, a compression test is next