Just wanted to share a simple fix as it may help others who are not super mechanically inclined (I count myself in that group). I've been running a TroyBilt 27 ton splitter for years. Original purchase was 2006. It's got the little Honda GX Engine, and it's never failed me. Last fall I changed the oil, hydraulic fluid and hydraulic filter. Fired it back up and split for a while, and it started really bogging down and smelling like gas. So I think it's the carb. I check the fuel line, it's clear. Check the oil level just in case there's a low oil cut-off or something, it's fine. I pull the carb, take it apart, it's sparkling clean in there, but I blast it with carb cleaner anyway, put everything back together and it fires right up. I run it for a few more minutes and shut it down thinking I'm good. The next time I tried to start it, nothing. Won't even sputter. Long story short it was the non-visible end of the spark plug. It was completely gunked over. So I applied heat to it, then took an emory board and lightly sanded the crap off of it. Reinstalled the plug and problem solved. Anyway, hopefully this can help somebody else out there.
Now obviously those things you did had nothing to do with the engine not running right, but it does make you wonder if you did something?!?! Nice job figuring things out and getting yourself back in business.
I should have really extended my comment a bit. As WS67 mentioned, if a plug is really bad, it often points to other problems. A really dirty air filter causing the engine to run too rich, engine starting to wear and burning some oil, etc.