No Gas to the Carb When Engine Warms Up

Pin holes will be witnesses, except when they occur higher than the fuel-level in the tank.
I severe restriction, on the suction side, can cause the fuel to "boil" in the line as the pressure drops. Now you have both liquid fuel and gaseous fuel in the line. That would explain the engine running on the empty filter I suppose......... cuz it's not actually "empty", but rather full of gaseous fuel.
And once again, the fuel flow test will show bubbles in the pumped fuel, that should not be there.