About the only thing I have to offer without knowing more is that since you've just recently switched to 10% ethanol it could be that some of your carbs need recalibrated for the new fuel.
Ethanol enriched gas needs much richer AFR's to run properly, especially a lean calibrated carb. Most of the work needs to be done in the idle circuits and can affect how the car starts, runs, and idles as a result.
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