I have a 1978 glassmaster super bassmate with a 1978 evinrude 115hp outboard. It's a 16ft tri-hull, with a 19 pitch aluminum 13 1/4 prop. The motor takes a few tries to fire up, but when it does it can hit 7,000+ rpms easily in idle. Whenever I have it at full throttle, however, it can only hit...