First, air filter, is it cleanish... a super dirty air filter will stall it at idle.
Second, you cleaned the carb, did you mess with the idle set screw?
third. won't go up to peak RPM, when was the last time you looked at the exhaust port? I just cleaned 1/16 of an inch of crud off my piston and head, there was only an opening the size of a pencil in my exhaust port window. the rest was carbon funk. An amazing difference was it was all cleaned out. I used fume free EZ Off. took 6 cleaning but it all came out of the head.
Fourth, I'd go looking at the point gap and timing, maybe even check your spark plug gap, or change it out.
Hope that helps
p.s. do you have spoke rims or mags?