I have a 1985 diplomat w/a 170hp merc. I have a hesitation on take off, with all of the characteristics of an accelerator pump problem.you open the throttle up all the way on takeoff & the engine stalls or backfires.this is no good if i want to ski i'll never get out of the water. So, I did a tune up the works, i set the dwell, point gap. then i did the accell pump, the in line filter at the carb & the filter in the bowl of the fuel pump.tightened the intake gasket bolts the carb base gasket bolts. the boat still hessitates & i've also been tweaking the timing to no avail. any sudgestions?