[steplift20]

lets not go crazy thinking the worst
it sounds like a fuel problem to me
do you have a fuel/water sepperator?
if you do change it also check the vent line on the outside of the hull make sure its clean and open
could also be an electric problem
stator/switchbox
oh wait i just remembered the switch box operates half of the plugs so went it cuts off it will shut them down causing half to get wet
while its running bad be careful and pull 1 wire off hold it to the block and see if your getting spark then the other side if no spark the switch box is the culprit
you didnt say what kind of engine you have
i had the same problem with my merc but it was sounding the oil alarm it depends on what switch box is bad it would run great then throttle would cut to half speed with the oil alarm going off