Idle problem

It,s not a miss. It shakes or rocks like it's in a paint shaker. The plug wires appear to be good, MSD 8mm wires. Thanks for all the input. I think I'm going to start by cupping the carb to see if there is a vacuum leak and go from there. When I installed the Airgap, I had a bad time trying to start the bolts in the manifold. Almost like the heads were milled, but they were not.