might need a new air filter,take the air filter off a run it.
Could be a dodgy spark plug.
Dodgy coil.
Had this happen to me once,my rotary moved in the van a sat on my fuel pipe starving the pump.....
also check the wires under the carb,clean them at the connectors,dirt can cause a bad connection,maybe loose connection on the battery....man i hate when machines go down...