[HotZ28]

Check your plugs again and see how each one is burning compared to the next one. I have seen new sparkplugs installed that have a broken ceramic insulator causing spark scatter. I have also seen new (non- Delco) brand wire sets with one or two bad wires. See if you can isolate the missfire to one cylinder and change that plug and wire with another cylinder to see if the problem moves with the change. Aftermarket carbon core (rf supression) do not work well on the DIS high voltage system from the getgo. Several years ago, I put in a new set of Autolite wires (carbon core rf) that were fine to start with but started missfiring after about 2K. I replaced them with spirl wound cooper core MSD wires and have not had a missfire since. Typical carbon core wires have anywher from 10K to 25K ohms per foot of wire as opposed to the spiral wound copper at 50 to 150 ohms per foot. Huge difference!!