Joe
The first thing I would check is the internal metal filter screen in the pump side of the carb. Often the problems your describing are created by low fuel delivery.
The screen is easy to remove, clean and replace if your careful. Flatten it blow it clean with carb cleaner and push it back in to the bottom. If you see any debris in there at all you may have found your problem. If it is all crapped up you did find your problem.