After running the car a few days I've realized that the excessive lean/low idle speed condition I see after coming down from a period of aggressive driving seemsto mimic what I see after restarting the car after it has been shut off for a short time (10-20 minutes).

The same excessively lean mixture (AFR gauge pegged at 18) and very low idle.

I'm wondering if I'm seeing some sort of fuel boiling/expansion thing happening
here, and if so, what I have to do to address it.

I have the factory one-piece heat shield installed; the exhaust manifold is also ceramic coated. The carbs are mounted on rubber couplers, so there shouldn't be much heat transfer happening there. I am using an electric cooling fan, which rarely comes on this time of year.

I'm wondering if the E10 fuel is the heart of the problem, and what sort of unusual measures I might have to take to address the issue if the fuel composition is in fact causing the problem.

I have a 140 series airbox that I could adapt to the Mikunis', and pull in cold air from behind the grille. The other thing I can think of would be to try re-routing the fuel hoses and possibly rig up some sort of heat shield for them.

Beyond that I don't know... hood scoop? move to another state where I can still buy real gasoline? I have zero interest in converting to fuel injection at this point in time.

Bill