loses power

I have a 2001 Utopia 185 with Mercury M2 210 hp (carburetor version). Used to go 50 mph, but started missing intermittently at high speeds a few weeks ago. Got worse and worse until now it won't go above 40 - rpms are down too. Starts and runs fine up to about 3/4 throttle - when I full...

I have a 2000 islandia that has issues, when the boat gets less than 1/2 tank off gas it will lose power when at 1/2 throttle to full throttle. it just stops going and then it climbs back up. if the tank is full it doesnt happen, its kind of dangerous with my kids riding behind on a hydroslide...