If you have problems with your car stumbling or hesitating when you try to give it some throttle, whether it is off idle, or when you're driving down the road, then you most likely have an accelerator pump issue going on.
The best way for you to get the info and detail you're looking for about this topic is to watch the video below.
95% of the time, stumbling and/or hesitation issues stem from this on your carburetor... the accelerator pump. Watch the video to see exactly how to solve the problem.
Another common culprit for causing hesitation and stumbling are the squirters. Again, watch the video to see what the problem may be, and exactly how to fix it.