Help with problems

[CHANMADD]

Sounds like it's sucking air on the drivers side bank..

[Tim7139]

Primary accelerator pump may not be kicking in early enough, possible the primary float is too low, lastly I'd check for a possible break in a driver side plug wire. Probably it's the accelerator pump

[ACademic]

Don't ignore a torn diaphragm (power valve) on the primary side of the carb. Loads up off idle (too much fuel) and can cause severe hesitation and/or a backfire. Once underway the engine is able to burn off the excess fuel that the torn PV is causing.