Replaced the plugs in my boat this past weekend(03 Sportster 155hp), getting on plain it hits 7500 to 8000 rpm, then drops to about 6700 after it plains out and doesn't run but between 35 and 40 mph, people i've talked to said it should run 50 mph with light fuel, no check engine light, had complete pump, ride plate and intake grate replaced last summer after i baught it, previous owner thaught it was ok to sit in salt water, long story, after that work was done the dealer water tested it and found it was pushing anti freeze, they found the head gasket bad and the head at the center cylinder was just a touch out of spec, so they just did the gasket, sounds like alot but i didn't pay a whole lot for the boat, going to do a compression test this weekend, the dealer said the compression was low but with in spec after the gasket was replaced, going to take it to the dealer next week to hook it to buds to see if anything shows up, they said it might be the tps not letting the rpm come up, just need some advice