First, welcome to OCC
You mention "rebuilding the carb". Has it been completely disassembled and have you made sure all the passages are clean? Have you made sure the tiny holes in the adjustment screws are clean? Did you use carb cleaner and made sure it came out of the passages ? Did you get a Kohler carb kit? Is there slop in the shaft for the choke? ( does the shaft wobble in the carb bores ? )
Jeff