Thanks for the replies all.

OK, so I have replaced the plugs, plug wires, cap and rotor. So far nothing has fixed it.

I noticed an occasional small backfire. Would a bent valve cause a backfire and the rough running? I am guess from your response that the rough running could certainly be a bent valve.

I was thinking it might be timing, but that darn missing electrode from the plug has me worried.

Also the check engine light occasionally comes on. I checked the LED under the carpet and it gives 10 quick flashes then pauses. I am looking for the error codes, anyone know what this might indicate?

Regards,
Java