Mitsubishi Repair: oily plugs, valve stem seals, spark plug wires

Question
I recently replaced my plugs (98 mitsubishi eclipse RS 2.0L non-turbo  automatic) I realized that my #4 plug wire had not been connected for a while.(cross country and back) total of about 25000 mi. Now the hole for that plug is always filled with oil. What happened? what do I do?

Answer
Ron,
If the plug wire is not connected into the spark plug, the piston will not fire.  Though the piston is not moving, the oil pump is still pushing oil throughout the engine.  It doesn't know your #4 piston is not moving, so it's still thinking it needs to lubricate and send oil around it.  Oil can eventually accumulate in the spark plug well, and foul the plug.  It's also possible your spark plug wire is not making a good to the plug.  You may need to replace your spark plug wires as well.

If oil continues to accumulate in your spark plug well, then you could have leaking valve guides, valve stem seals, or possibily a leaking valve cover gasket.  The valve cover gasket can be changed in your own garage for a cheap price.  Replacing guides and valve stem seals will require a professional, and hundreds of dollars.  Try all the cheapest fixes first before going for a valve job.
Good luck!