I agree with Ted. With the engine off look down the carb throat & work the throttle. Each time you open the throttle a squirt of gas should go in the throat. Also check your float level. If it is too low it will cause this problem. Notice what size main metering jet is in it. It should be stamped on it. It is usually is 53-55. Sometimes these rebuilders put in any part that happens to be handy.
