I vote on Holley type carbs also but with the Edelbrock there should be no reason to mix race gas unless the fuel in your area is known for being bad.

My car has pretty much ran great all summer but I've had an intermittent problem like yours where it will stumble and stall and not run right. After alot of parts blaming and parts changing I finally watched the carb closely the other day and the rear bowl would just fill up and drip out of the boosters. My fuel pressure was at 7 but I have a cheapo gauge, so I backed it down to 5.5 pounds and the car runs perfect, simple fix on mine.

Good luck with it.