I'm not being obstinate about testing procedures, just sharing your frustration. Chronic flooding can be an extremely aggravating problem and I've been in your situation numerous times. Occasionally it's just a poor fit between the needle valve and the seat and no amount of adjusting and tinkering would solve the problem. As long as the engine is running above idle, the liquid level in the float chamber doesn't rise above the level of the venturi, which allows fuel to spill over into the air stream and cause the flooding. The next time it starts to stumble and run rough, shine a bright light down the carb throat and see if there's gas dribbling out of the venturi. If so, that's a confirmation of a flood. There should be NO liquid gas visible in the carb bore. We used to be able to buy just the needle/seat assembly without purchasing a whole rebuild kit, but those days are long past. Does your needle valve have a rubber tip. or is it just a tapered metal to metal seal?
Jerry

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