The plug on the left is out of #5, right is #7. If you look at the headers you can definitely see a lack of color on the #5 runner. The plug looked brand new, opposed to its neighbors that were sooty from the rich tune. I’ll double check spark on #5. I have to think of a way to check the fuel injector for that cylinder.
Does the Holley have a test mode to test injectors and coils? Something to allow you to cycle them individually high/low to confirm your wiring is good before you dig in too much further?