Originally Posted by mbzman

Does it go beyond 100C? I won't let it. Mostly stays ~90-95 but, took a turn today and 85-90 mostly.
Not sure where the M119 R129 normally sits engine temperature wise. Has 80C stat. I put new yesterday.
Moisture is created in the combustion process and it sounds like it is being burned off. Coolant level seems to stay at its same position in the canister.
Continue to monitor coolant level. When was it last changed? At this time of trouble w/AL approved - Prestone.
Are you using the correct MB fluid? Not sure about the misfire. It actually is not rhyme but out of a regular step suggesting detonation.
Plugs, filters, wires are a good place to start if they haven't been done in a while. Is your wiring harness original to the car?