I had a similar problem with an older Q-35, points, 25-1 fuel/oil ratio. Always ran superb, then I mounted it in another plane, and it would die after about 10 minutes. Well, back to the basics. I went to the original engine manual. Reset both the H and L needles to factory settings - 1 and 1/4 turns open for both, and restarted the engine. Ran a bit rich (slightly), but I left it there and went flying. Presto - full flight to idle touchdown.

I suspect your L and H needles need to be returned to factory 1 and 1/4 open - too much tinkering and they are probably way out of synch with each other. Try it and let us know how it works. The settings are good for all Walbro carbs up to 100cc.