I have a 1993 fourwinns 210 horizon, owned boat since new, has omc 5.8liter efi engine, 450 hours total usr, up until 5 years ago used boat alot but the past 5 years only use it for ten days each year, problem is boat seems to miss, has no power, & if get planed out top rpm is only 3100rpm, in neutral boat seems to run fine, upto 4600 rpm, i have done the following already, cleaned gas tank, checked vent,changed filter,checked fuel pumps, replaced distributor cap& rotor, replaced sparkplugs, unhookedoil pressureswitch but no change, hooked up code reader &system passes, my amp gauge reads 13 volts when engine running with no accessories orblower on, if turn blower on while engine running amp gauge drops below 13, is ther a voltage problem or possible fuel injector problem or maybe corrosion inside thedistributor, the cap& rotor were corroded bad but never looked any deeper at distributoro