Honda 50 fuel starved question

I recently bought a used 2001 Honda 50 hp tiller handle 4 Stroke. Engine sat for a couple months then I bought it. Bought a battery and a "universal" 3/8 " gase hose and all the Honda fittings for the portable tank and gas hose. Engine started "right up" on first push of start button. Cruised around at all different speeds for a while and suddenly engine started to sputter and cut off. I pumped gas bulb and it started right back up and ran fine then started sputtering again. Engine runs fine a low speed but when I start twisting the handle it excelerates fine for a while then starts sputtering and I pump the hose and it stops sputtering.
1. I changed the fuel filter figuring it was eaten up from sitting with fuel in it.
2. Started doing the same sputtering issue but not nearly as frequent but still doing it

Should I buy a bigger diameter gas hose?? Is this aftermaket "gray" gas hose a piece of junk?? It is a fuel starve issue. Any help

Did you make sure the vent on the gas tank was open?

5/16" is the normal size of the fuel line. 3/8" is ok if the fittings are 3/8" and the correct fittings. If they are the official Honda fittings, they will be too loose on a 3/8" hose.

Are the hoses connected tightly on the hoses? You should not be able to rotate them. You could be sucking air at high speeds.

If is possible that your fuel pump is bad, but I would check out the hose issue and vent issue as freeportd suggested.

Mike