[bobbert]

Have been dealing with your problem for at least 6 years here in the Northeast. Major problem is that E-10 is blended at your local terminal. Up here it has been found to vary between E-10 and E14. Any excess ethanol over E-10 is an instant problem. Down in your area things are made worse by the high humidity. Remember ethanol is a major component of DRY GAS. It traps the moisture in solution and in theory is consumed by you engine.
Up here I have found the only solution to be the constant addition of Startron.
Up here the high variability of Ethanol content is also wrecking havoc with gas station fuel tanks. Those special double wall glass tanks are starting to fail and they are installing EPDM bladders to seal them up.

Good Luck with your problem and hope and pray the dictators in Washington don't decide to make E-15 the new normal.

Last tip. Try to find out when the station of your choice gets their tanks topped off. Try to purchase right after they get filled up as the filling process remixes the ethanol and reduces the Phase separation in their tanks.