That is possible. I am just now getting into carbs, so you'll have to pardon my ignorance, its a learning curve. But then again, its all shear mechanics and pretty straight forward for the most part.
I know my old EA81 Hitachi had a hiccup when I'd rev it more then 1/4 throttle off idle. But then again, my carb was original and probably worn. Once it was off idle, you could rev it WOT with out any issues. Just of idle it would stumble.
and there is a strange tinging sound at around 4k rpm. Sounds like it may be the exhaust where the heat piping ran up to old engine. down below the passenger cv axle.