Mitsubishi Repair: oil on #1 spark plug, valve cover gasket, gasket material

Question
My check engine light just came on. I could feel a sudden loss in power. My preliminary check was the fluids, all of which were fine. I pulled the #1 spark plug, and found oil. I checked the rest of them, and they were fine. I'm hoping that its just a plug seal, but before I pull the valve cover off, I wanted to ask for an opinion. Am I on the right track?

Answer
Rich,
I think you are on the right track.  Over time, the plug seals harden and do not provide a good seal.  Oil can leak down into the spark plug well and pool up.  When enough oil pools, it can soak your plug.  That will foul your plug and cause occasional misfires.  You'll definitely notice a loss in power if all your cylinders are not firing properly.

If your car is more than 5 years old or 70k miles, replacing the valve cover gasket is a good idea.  Just be sure to clean off your valve cover extremely well when it's off.  The will ensure you get all the old gasket material.  Also, if your valve cover is cracked, you will notice it much better on a clean valve cover.  I find carb. cleaner an excellent solvent for removing grime from valve covers.  Be sure you torque everything back to spec.  Many valve covers are aluminum and crack very easily when over-torqued. Replace your PCV valve while you're at it.
Good luck!