Poor hot idle caused by ethanol gas? Whaddya think?

A trick that I have used in the past for carb heat insulation when you do not have room for a spacer or do not want to use a spacer:
- drill out the carb mounting holes to 7/16"
- use some insulation over mounting bolts/studs. Heat shrink, or some spark plug lead sheathing often works well
- fit the carb base gasket. Use fibre washers under a plain washer on the mounting bolts/studs
- do not fully tighten
- move the carb around until none of the fasteners touch the body. Then tighten.
- no metal to metal contact to transfer heat. might not be as good as a spacer, but better than nothing.