Before you dig into the carb, check your point gap, as others have said. It may very well be the carb, but it's a lot easier to see if you have a worn rubbing block causing the points to have a very small gap.
Another possible problem (one that I had on my Bolt) is worn distributor bushings. When this happens, you can set the point gap (dwell) and on the next revolution of the distributor, the adjustment can be out again. I finally went to an HEI distributor and haven't had a single point problem since.
