Sounds like fuel restriction or possibly the fuel pump is sucking in air from somewhere.

I had a cracked 6" fuel hose coming off of the gas tank that caused me grief like yours for several weeks. It didn't leak gas but sucked in air. Replaced it with fuel injection hose and problem was solved.

If the carb and fuel pump are new or in good shape go over your fuel line back to the tank and your fuel sending unit in the tank.