I have received one of those carbs where the fuel seat was not pressed in far enough. I think these are either untested, or failed units they sell. Cost more for them to take the return than to just ship another. I have the same running issue, ( not electrical) on two Kohler single cylinder engines SV590. Either surges badly or runs for short time on 1\2 choke. I have tried all new gaskets, governor adjustment, and valve lash. I'm really interested to see what you come up with here.