Like Dave said, we're too far apart to actually be hands on to hear and feel it. Change the plugs to insure firing. Double check heat ranges. I'm assuming non-roller cam so the distributor gear has chewed itself up and came out of phase. Stay with the little things like plugged metering block on primary side of carb. Clean plugs at right heat range, etc. You said you used a timing light to check all eight, were all eight flashing at their correct timng marks? Just a thought.