Not running properly and oil found on one of the spark plugs, what would cause this?

Hi,

If the oil on the spark plug was on the porcelain portion (inside the spark plug tube where the coil attaches), the valve cover gasket is leaking. Each one of the spark plug tubes has a gasket to prevent oil from getting in there. It sounds like one has failed.

If you look at pic 1, it shows the top of the cylinder head with the valve cover removed. I highlighted where the gasket goes. Note that it goes around 4 circles. That is where the spark plugs go down into the head. That needs to be sealed or oil gets into the spark plug tube.

Starting with pic 2, I included the directions for removing and reinstalling the valve cover.

Let me know if this helps.

Take care,

Joe

See pics below.