it still sounds to me like you have a dirty carb
if it was as bad as you say, I doubt soaking it in anything will clean it really good
sounds to me like its going to need a rebuild kit for sure, and all hard parts to maybe be in a ultra sonic cleaner a while to get things to where they should be
you can also, try removing any soft parts(effected by heat) and boil the carb/parts in lemon juice,, its been known to work better than soaking in carb cleaner!
ethanol fuel over time forms a varnish coating to all parts and passages and it seldom comes off from soaking, its just too hard already to come off that way, , so, replacing parts that you can with a rebuild kit will sure help, but it won;t help in other places
so, to me, its either boil or a ultrasonic cleaner to get carb to where it needs to be, when there this bad!