Ethanol should actually boost the octane level of your fuel. The octane boost that has been referred to usually has ethanol in its makeup. The most likely reason for poor engine running when switching to ethanol fuels is that your car is not set up for the higher octane level. Not sure how these EFI motors work, but with my carbie style motor in the Torana, I have to adjust the timing if I switch to higher octane fuel, or it pings or runs poorly. I would guess that the Tarago's timing is controlled by the computer, which will mean a trip to the mechanic to have your timing redone. HTH
