Start by doing an "upper cylinder lube" procedure. Get a can of Marvel Mystery Oil or some other lightweight tuneup oil, run the engine at a fast idle, and slowly dribble the oil down the carburetor throat until you get a heavy cloud of smoke from the tailpipe. Then dump enough oil in quickly to stall the engine, or shut the ignition off after giving it the heavy dose of oil. Let the engine soak overnight, then crank it with the throttle wide open until it starts. Goose the gas pedal several times and run the engine at fast idle until the smoke clears. If there are carbon deposits on the intake valves that cause them to stick intermittently, this procedure usually cleans them up. Warn your neighbors what's going on in advance, or you just might get a visit from the local fire department- - - - -the smoke screen will be epic!
If that doesn't help, then dig into the carburetor and inspect the accelerator pump circuit.
Jerry
