Dave - sounds like vacuum leak. may also be partial plugged vent to float chamber, will cause fuel level to starve/surge causing lean mix. Simple test and check for vacuum leaks. Start engine and fast idle (no breeze) use small propane torch to check. just turn on the gas, no sparks. go over all manifold junctions and hoses and carb base. you will know when you find the vacuum leak as the engine will increase RPM. Think Chevy!
