Ford Repair: 95 Ford Taurus Ignition, smog test, wire tester

Question
Would the valve seal cause oil fouling or carbon fouling?  I have carbon fouling.  The car has 92k miles on it.  I bought a spark plug and wire tester and it shows all plugs and wires working fine.


-----Question-----
I was just wondering what could cause a single fouled spark plug while all others are perfectly clean after a small amount of driving (less than 1k miles)?  I have a 1995 Taurus SE with the middle front spark plug fouled.  It has new plugs, wires, distrbutor rotor and cap.  This one plug is causing a failed smog test.  HELP PLEASE!?!?!
-----Answer-----
Brooks,

It is possible that the one cylinder has a leaking valve guide seal causing oil to be burnt in the cylinder. How many miles are on the car? You could try using a spark plug non-fouling adapter as a cheap fix until you can fix it right.

Answer
Brooks,

Yes, a leaking valve stem seal will cause fouling and carbon build up. If it is bad oil drips into the cylinder and gets burned leaving behind the carbon. It probably is not enough oil to notice a drop of oil level, but enough to foul your plug.