First thing I'd do is check the plugs....This will be a tell all....Sometimes when you nail the gas and it pulls well till 2500 or so then falls short you may be running out of fuel? Plugs will tell this...

Dark or black....no

tan or light....yes

Atleast thats what I get from it....

Plug reading can tell you alot about tunning a carb...I run on very light pedal for 30 miles...jump out check the plugs....then run it just hard enough to use the power valve...check plugs....

Make a hard full throttle pass...let up...turn it off and....check plugs.....Usually I do 2 in a row on the same side...so you get off both runners.....enjoy