What should i do about the oil on my spark plugs?

I have a 1986 camaro 2.8 V6 and its been acting up lately, hesitating, sputtering, etc. I replaced the distributor and spark plug wires but no luck. then i discovered the car ran better (still not perfect of course) when the #6 spark plug wire was disconnected, so i took the #6 plug out and it had oil all over the thread. this is the only plug that had oil on it. i dont know much about cars but obviously oil shouldnt be in there. does anybody know what it could possibly be or how to fix this?