1993 300E2.8, 72,000 miles. Starting about a week ago, I have had a hesitation and misfiring problem went the accelerator was first pushed from idle. At higher rpms, I never heard a problem. I knew the spark plugs were past due so I changed them. When I got to the back plug, it was covered with oil when I took it out. After a little investigation, evidently when my head gasket was replaced at the first of the year and 10,000 miles ago, they stripped a valve cover bolt (actually the threads the bolt goes in) that is underneath the connector on one of the coils. I pulled the bolt out with my fingers. I guess it has been getting a drop of oil now and then from the valve train since the bolt did not seal like it was supposed to do. The oil drained to the last plug hole and started filling up and covering the plug. When the level reached the magic level on the plug last week, it started misfiring.

Anyway, the misfire is fixed now and tomorrow I am going to complain like mad to the dealer that fixed the car and see what they will do about fixing the cause of the problem.