I have a BS 135202 with a pulsa jet tank mounted carb on my go-kart. The engine was "surging" or "hunting" at full throttle. I would be at full throttle and it felt as the throttle was temporarily released (which it wasn't) then it would immediately retain full power. This process would repeat intermittently. I disassembled the entire carb and soaked it for 30min in chem-dip carb cleaner, hit all the jets/passages with compressed air, and got rid of all visible dirt. I reinstalled the carb with new gaskets and the problem persists. Any ideas? I thought it could be the idle mixture screw, but adjusting that didn't seem to help. Please let me know what the issue could be. Thank you.