I think goose may be onto something. I have had my car run a bit like you describe and it turned out that the secondaries weren't opening because something was in the way of the plates. I have no idea of the configuration of your Carter carb but I would check that first as well. Push the throttle linkage open and look down the throat to see if all the plates in the bottom are open fully. It very well could be an ignition issue too. Bad points or cap.