Ok, I'll try to explain this as best I can, bear with me.
First off, we had the engine and outdrive overhauled/tuned up and it has ran great for 3months, skiing every weekend. about 2 weeks ago we started having problems.
The boat will start, takes a couple cranks when cold but starts right up when warm. It will idle but the rpms will putter down to like 5-600 then just before it stalls it will rev up again. If I give it throttle it sounds like it powers up normally but if I leave the throttle forward it will do the same thing as at idle, rpms will go down then up, but not down low enough to almost stall. When the rpms are down the carb makes a hissing noise, then it revs back up. I've adjusted the idle back and forth and it doesn't seem to solve the problem but that's the only thing I know how to adjust on the carb.
I obviously don't have much experience with engines but I'm trying to learn, if someone could point me in the right direction I would greatly appreciate it.