I have a 1987 Procraft 1780V bass boat with a 1986 Black Max XR2 150 Serial # OB122507. I have own this boat since 2010 and have adjusted the jack plate, replaced prop with a 23Tempest +. It used to run 55-56 mph @ 6000 rpms. I replace the replace the plugs, fuel filter, primer bulb and correct...