Did you smell it? Might want to try and remove some of the fluid from the threads and see if it's engine oil for sure, or gas, or coolant.
I forget how these motors are numbered, which are we talking about?
Just a hunch, you may need to change the factory intake manifold gasket. My FelPro replacement from a typical parts store made the factory cork dealy look ridiculous.
Also be on the lookout for engine pinging. Whatever is getting into the combustion chamber and making that plug look like that might be contributing to hot spots in there which will make that cylinder ping. If pinging/detonation go on long enough you just might put enough stress in to break stuff or prematurely wear it out.....blow seals out, cause leaks etc.