My 1999 250 Ox66 was running great for a 50 mile run. Had topped of the fuel before leaving to the very top and burned through 2/3 of the tank. When returning to the boat for the return leg there was 1/3 tank left. Started the boat and seemed rough, would only go to 3500 RPM. Stalled a couple of times and blew off a ton of smoke on restart. Got home on fumes with nothing left in the tank at all. Was ready to check the O2 but pulled the plugs first to inspect. The sparkplugs at the TOP of the left and right bank had "no gap" left while the other 4 plugs were gapped to spec. Top two were closed, and could just slide a piece of paper through there. All plugs were black but not wet.

Any feedback appreciated......very strange