OK, if you are disconnecting the liquid hose BEFORE it enters the regulator/vaporizer you should get LIQUID fuel out when the lockoff solenoid is energized. That part of the hunt is not a defective condition. The fuel is supposed to be in liquid state when it enters the regulator/vaporizer.
What kind of hose do you have that leads the vaporized fuel to the mixer (part you are calling carb)?
Unless that hose is rated for LPG service, the inner hose liner layer might have swollen and is now unable to flow the volume of fuel needed at higher RPM and power demand.
A constricted vapor hose will also cause fuel deficiency because the engine induction vacuum (that is supposed to unseat the regulator secondary valve) will be greatly reduced inside the regulator secondary chamber.
For this engine, the vapor fittings at the mixer and at the regulator should be 5/8" size.