Hi, My 1982 70Hp Mercury all of the sudden started bogging down at full throttle after running it all day. and ran great up until that point. turned motor off fished for an hour started up and idled fine but would bog down at more than .25 throttle but would run full throttle with primer bulb being pumped. Any guesses as to what it could be? do i need a new fuel pump? or is there a possible air leak in the line?