Hi - I've got a 2001 Johnson 150 Ocean Pro, it was running great at the start of the season with new plugs in it, however on the way home from a fishing trip, the engine began to bang every so often, it looked as if I was hitting something or a cylinder was occasionally misfiring. It happened more often at higher rpms and also seemed to be a harder "miss" at higher rpms as well. I limped home for an hour at 8-9 mphs, toward the end of the trip I increased speed slowly and it ran fine - up to 4400 rpms / 24mph. I pulled the plugs and the port side lower plug was pretty well fouled(black wet soot) but there was a gap on the plug, so I replaced it. The others looked fine. Haven't restarted it - my question . Do you think that was the problem??? , and more importantly what do you think caused it? 
Thanks for any help

Thanks for any help
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