to answer the first question, 10% ethanol would definitely NOT cause any code.
If you used a much higher percentage of ethanol, such as E85, it very well might set a lean code, but not a rich code
As for figuring out your problem, you replaced the two items I would have suggested off the cuff. If you haven't done it already, I would definitely be checking fuel pressure.
Misfires cause lean codes btw. It definitely won't be an ignition problem, EGR problem, vacuum leak, etc. Very few things cause rich codes