Can't increase power on a Mac 280B Blower?

My Mac 280B Blower will idle but wants to die when I try to increase the speed. It idles only in half choke. I have checked the exhaust port to assure open exhaust, changed to new gas, cleaned and replaced the air filter, installed new gas lines and can't find the problem. Anyone have any ideas? My only thought is to disassemble the Carb and completely clean and rebuild.