[Wbulk]

I second Jim's opinion. You were on the right track because it ran good for awhile when you cleaned it. Take the idle and primary jets out and blow carb cleaner through the straw in the jet holes, in the idle transfer slots, and down the air bleeds. You have some debris in there that is moving around. There are various opinions about that carb but there are thousands and thousands in use. This problem also happens to Holleys and oh ya my lawn mower to. All carbs are old designs, that's why they went to fuel injection.