Edelbrock 600 carb issue?

Here is a photo of one of the plugs. I know, they are almost completely ashes over so I wire-wheeled them and put them back in and did not help the issue. Underneath all the deposits they looked to be in good condition. Today checked the metering rods and they are stock 74-57. Haven't disassembled carb yet but a carb rebuild is my next try at fixing this, hopefully this weekend. If that doesn't fix what would be the next thing to look at?