IMO, champions are crap. They never come gapped right and the ceramic insulator sometimes fails earlier than other plugs. Always gap new plugs nomatter who makes them, chances are that at least one is off. A good set of plugs and wires is a cheap way to get a little better preformance and fuel economy. Bosch have never let me down. Also, if it is sluggish it wouldn't hurt to check the wires while you're looking at spark. The way the burn runs down the side of the ceramic insulation leads me to believe that the insulators are bad and the spark is jumping to the head instead of staying in the plug.