Nobozo
I did not know about the Anti-Siphon valve either, until a mechanic told me to check it.
Apparently, what it does is prevents the tank from emptying inside your hull if you should develop a leak (at least what he told me). It is a 1 - way valve from the tank to the vent. If fuel runs out of the tank too fast, the valve will close and create a vacum in the tank. Mine was all crudded up with an off white crusty buildup, probably from ethanol.
The Mechanic I was working with told me that this would make sense for my problem - because the boat will run fine at idle, but when you push the throttle down, once you burn off the fuel in the carb, you can't pump enough fuel back into the carb to keep it running above an idle becuase the valve creates a vacum lock in the tank. In my instance, if you let the boat sit for a half hour - it will run fine again - which would make sense as air gets back into the tank to break the vacum.
I am no expert - just adding what limited knowledge I have to help a fellow boater.
Hey BigDog - I carry a wrench that fits my drainplug on the boat at all times, much easier and quieter than the C-4
