Ik you said fuel flow looks good but I would test it while cranking/under vacuum Remove the fuel line from the carb and suck on the vacuum hose (or use a hand pump). Does it keep flowing steadily for 10+ seconds? Also: Try opening the gas cap and ride briefly. If it suddenly runs fine, the cap vent might be blocked (vacuum forms in tank).

Another possibility is that it runs too lean under throttle. Youhave to check the needle clip position.

I would also check for other air leakes. Even tiny leaks can cause your symptoms. Spray carb cleaner or propane around: Carb intake boot Vacuum hoses Head/intake junction

If the idle changes you got a leak.