New engine issues

What brand of wires? What is your static and total timing? Are you running a vacuum advance and if so have you tried it unplugged? Low Octane won't hesitate, in fact it likes to ignite sooner than higher octane, poor gas, as in water contamination will, but usually you can smell that. The Carter/Edebrock carburetors like a certain fuel PSI and no more, are you running a regulator?