Ford Crown Vic, Mercury Marauder, Grand Marquis
I have a 1997 Grand Marquis. It had a misfire a few months ago in cylinder #5. I changed all plugs, and saw there was oil on the plug, above the seal. That is, it must have benn in the spark plug well. There was no oil on the threads, or the electrode.
The misfire went away,
Then two days...