You didn't mention how long it's been on the road. If it is varnished up it should clean up over a little time and driving. Sometimes and only sometimes you can rev it up a ways with the air cleaner off and quickly cover the air intake with your hand till it starts to die. That makes for a strong vacuum and could help clear any passages. The idle circuit is not used above idle but the momentary closing of the carb might help clear the junk out. I would put some miles on it and look for vacuum leaks like Joe says. You could get some rubber carb caps and plug everything pertinent and see if it improves. Good luck...
Liz, covid, murdered 10/19/21