AFR readings

Car is a drag car only. For years I used to mix Sunoco 110 with 93 pump gas as I had issues on really hot days with the fuel boiling in the carb and creating a stumble when I tried to run just 93. I have since switch my fuel system from a dead head to a by pass system to help keep the fuel cooler and have went back to straight 93. When I was mixing fuel I was doing 2 gal 110 to 3 gal 93 and my AFR reading was 12.7 at WOT. Now with straight 93 it is 13.3. The car does have a snorkel style hood scoop and I didn't used to run an air cleaner, but this year I installed a 9" filter and used a K&N Drag filter (Grey and can pretty much see thru it). I need to install some new plugs to get a good reading on them, but this past weekend the car which is usually pretty consistent was deadly consistent in the 5 runs I made.