Engine died down at high RPM.

[tsubaki]

What boat do you have?
Better yet where are the fuel tank(s) located?
Almost sounds like a split at the top of the pickup tube in the tank.

[tsubaki]

Air in the line could be a number of things.
Usually it will straighten out by pumping the bubble till it's hard.
If no fuel leaks or smells are evident and the air persists, you may have to check the pickup tube coming out of the tank for a split.