Need help with my Holley

Out of the blue last Sunday my Duster wouldn't stay running unless I stayed on the gas pedal. Long story short I sprayed some carb cleaner in it and got it running right again. Took it for a spin and all was right with the world. Parked it for a half hour and went to pull it in the garage and the thing started again.
I changed the rubber lines that connect fuel line to filter and did the carb cleaner thing again. Eventually it cleared up again! I've checked all the electrical. I changed the plugs. Old ones looked fine by the way. Carb was professionally rebuilt 2 years ago and performed great. It's 750 double pumper. A friend thought something might be cloggin the carb. possibly from the hoses deteriorating. Another friend thinks the floats need adjusted. Another buddy thinks it's the power valve. What do you guys think?