Poor hot idle caused by ethanol gas? Whaddya think?

I have no experience with E fuel in our old cars, but I can tell you this: it has no place being in a metal carburetor.
I keep E10 in the shop for parts washing because it is cheaper.
A few years back I left some in a container overnight, very mild weather. Next morning there water drops in the base of the container because E fuel is hygroscopic. At first I thought there had been water residue in the container BEFORE I put the E10 in it. Carefully cleaned the container & left it overnight again with E10 in it. Sure enough, water in it next morning.

The E fuel might have formed water in your carb &/or corrosion which is blocking jets/passages.