Denny, radio-frequency suppression "wires" are actually string impregnated with graphite and sometimes a few other exotic components. They spread the resistance out over the entire length of the wire, rather than concentrating it in one place like a resistor plug does. A good resistor wire will have a maximum resistance of 1 K-ohm per inch, so a 12" wire is good if it has a resistance under 12,000 ohms. The end result is a current-limiting effect that prevents, or at least minimizes RF field generation surrounding the plug wire as current is flowing across the plug gap. It's also why the spark that jumps from a suppressor wire looks orange/yellow instead of blue- - - -lower current flow. As wires age, the graphite tends to clump up in places, resulting in areas of very high resistance inside the insulation. Under acceleration, the load on the piston and the increased pressure in the cylinder requires a higher voltage to fire the plug effectively, and a tired plug wire that has increased its resistance over time isn't up to the task of providing the extra voltage demand.
Plug wires deteriorate from the inside, just like radiator hoses do, so a bad wire or hose is not obvious from a visual inspection standpoint. Some things just need to be changed on a time or mileage basis, not outside appearance.
Jerry
