I would not discount anything. Your symptom could be caused by electrical or mechanical issues. Check out and clean the carburetor again inside, even if you did it before, making sure the jets pristine. A small clog can give you big headaches. Readjust it from the start and see if it helps.
As suggested, weak electrical components and/or connections can cause the same issues of backfiring and effecting the ability to take throttle. Make sure your battery is good 12.8 volts and connections are clean and tight. Good time to have it load tested as well. Since your bike will start and idle check that it is charging min 13.6 to max 14.5 vdc. .
