ocassional misfiring '95 c-280

i have a '95 c-280. Every now and then, very unpredicable, it will misfire badly and lose power. It can happen when first starting up, or it has happened after stopping at a red light, and has even occurred while going down the road at 60mph. All other times it runs great, and problem can be corrected by stopping, turning off the ignition and then restarting the car. May not happen again for a couple of days.

I replaced the entire ignition wiring harness. Plugs are new.
Does anyone have any suggestions or similar experience? Pls advise and thanks for any help.

[Gilly]

I ran into a similar problem on a S Class car about this same year. I believe it has an early OBD2 system in it which uses what is called a "DM" (Diagnostic Module) for misfire detection. If it detects too much misfire, it can and will shut down the offending cylinder. The question is: which cylinder and why? A shop should be able to read out the stored trouble codes to determine which cylinder or cylinders are being shut down. It could be several things. The one I had, replacing the sparkplugs fixed it. It could also be a coil or the short part of the coil which connects the coil to the plug (available seperately). Lot's of possiblities. Are you getting a check engine light or not?
This scenario I am describing (DM shutting down a cylinder or two) will act just like you describe; shutting off the key will let in run on all 6 cylinders again, but there should be a stored code, possibly not in the engine control module, but definitely in the DM.

Gilly

PS did you or whoever put in the sparkplugs use the approved sparkplugs, Bosch F8DC4? Were they replaced to try to cure this problem, or did it start after the plugs were replaced?