78 Caprice hesitates from a stop, need help.

When the car is cold it hesitates pretty bad and I have to double pump the gas pedal to get it to go. After it gets warmed up it runs ok but still has a hesitation from a stop. This is on a 78 Caprice Classic with a 305 and 29,500 miles. It has a new air filter and new rubber gas lines from the fuel tank and in front of the fuel pump, new spark plugs, fuel tank and sending unit. I also checked the spark plug wires and the are within spec resistance.

I'm guessing that the carb needs to be rebuilt but I have no experience with this. Any and all suggestions are appreciated.

My wagon was doing the same so i put carb cleaner in the tank and after 2 tanks of gas it is running fine.