I fussed forever with a pair of carbs on my GS500.
Cleaned the carbs, lined the tank, cleaned the carbs again, rode for a week, acted up, cleaned the carbs.
I still have no idea why they got all shitty like that and it was so inconsistent.
Mine were mounted with boots and, if I remember correctly, had a diaphragm on top.
If I had to do it all over, I would have just spent the money on a dealer rebuild kit.
I feel your pain though.