Ive got a 1985 merc 90 that only gets to 4900 @ wot, ive fixed all electrical problems ( all new parts ) have great compression, new electric fuel pump rated @ 7 psi. the motor is on a 1970 aquasport 19.6, the prop ia a 14.75 x 15. ive checked it with an inductive tach and reading is true, boat...