Need help determine cause of missfire

Have you been swapping different plugs into 8?
Do you have power brakes?
Are you loosing Brake fluid?
Where is your PCV hose plumbed to?

If the plug is wet for whatever reason, the spark will leak down the electrode and short the energy to ground. The light will see it as a missing strobe. If you have swapped a different plug into that hole, and it still does it, then take an old plug and break off the outer electrode, then stuff that plug into the wire and lay it on the engine. then start it up and observe the spark. That will prove the wire. If the wire is good then put it all together; spark is not your problem.