Check your plug. Sounds like maybe you're running too lean (crazy acceleration while cold), and running the engine too hot (which is slowing you down). If the plug is almost white (too lean), maybe your main jet is clogged or you have a vacuum leak between the carb and the intake manifold. Check your points, too, just for good measure. You haven't messed with the timing (following some recent threads)? Too much advance will make your engine run hot, too. Just a couple of thoughts.