Howard,
there are two issues with ethanol.
Firstly is traps moisture in the fuel. as the water is immiscible it forms a layer or drops. When the water hits the engine the fuel dosing maybe right in volume but not in stoichiometric mix so you run lean.
Secondly the alcohol & water can attack fuel pipes , tanks, pumps etc. In my garden hedge trimmer it dissolved all the fuel lines in the tank!
