Excellent point. If it does have an accelerator pump on the carb pinch off one of the vacuum lines going to it. If you engine smooths out then you need to replace the diaphram.Be sure the choke is COMPLETLY off. The Keihin BCH carb used on the CV23 is very sensitive the the choke being partialy on, especially if it has an accelerator pump. Or your accelerator pump diaphram has a hole in it and needs a to be replaced. Engine spec and serial number would be helpful.