My 1993 300e 176,000 miles has started to run rough. I don't know where to really start with fixing it. Installed recently new wiring harness, MAF and fuel filter. Should I just start with the obvious? Plugs, wires and connectors? Perhaps a coil is going weak? Which one? I don't dare take it to Sunflower motors in Topeka, last time they charged me $488 to replace a coil and put in connectors on 2,4,6. What a rip off. I built a code reader and get the following codes (if it really makes any difference) I took the coil cover off just to check things out and now only 3 of the 6 bolts will tighten-up! Its almost like the threads in the head have gotten lower or something. How weird.

Pin #6 3,6,8,9
Pin #7 1
Pin #8 1
Pin #10 No lights
Pin #14 14,5,11

Any advice would be appreciated.
Rick Potter
Potters Barber shop
Osage City, Kansas