What you're experiencing is called a "surge", and it is actually running out of gas- - - -almost. The fuel filter is probably clogged, allowing the float chamber to almost empty before the fuel pump can refill it. If the filter is new and clean and the problem persists, there's either a problem with the fuel pump, or the line from the tank to the pump is restricted. Backtrack one part at a time from the carb to the tank until you find the clog.
Jerry
