One thing that can cause a rough idle

I've been having a hell of a time trying to get my 5.7 stroker in my drag car to idle. This is a new build, and I haven't done anything but start it up and idle it in the shop. Carbureted, open headers and a big cam. Thought the rough idle was due to the cam, but pulled plugs a couple of days ago and this is what #8 looked like:


New coil for #8 is on the way.