last yr, i pour some seafoam into my tanks, to take it out for one last outing to get the seafoam thru the lines. got to the lake n the boat won't plane. can't get any higher than 3.4k rpm. had someone sit up front, got her to plain but took 25 secs to plane. even then on plane will not go over 3.4k rpm. so i said f.. it n stored it for the winter. assuming it was the sefoam. spring comes along, i refuel with more fuel, took her out to the lake n same result. don't know what's wrong, am stumped. haven't changed plugs yet, could it be the plugs, blown cylinder, ???.