Can you turn off the fuel? If it smartens up as the carb bowl drains that will tell you something.
Does it have an impulse type fuel pump? Sometimes the diaphragm leak putting fuel into the crankcase. This doesn't fit your good idle though.
Carbs have air bleed passages that are just as important as the fuel passages.
I think you have weak spark. As cylinder pressure goes up with throttle opening it takes more energy to jump the plug gap. Try a 20 thou gap and see if that helps.
Does it have an impulse type fuel pump? Sometimes the diaphragm leak putting fuel into the crankcase. This doesn't fit your good idle though.
Carbs have air bleed passages that are just as important as the fuel passages.
I think you have weak spark. As cylinder pressure goes up with throttle opening it takes more energy to jump the plug gap. Try a 20 thou gap and see if that helps.
