Rather than purchase wires, can you bring them to your local Auto Pro shop and borrow their ohmmeter. Resistance should be somewhere around 3000 ohms for the length of cable (typical standard is 5000 ohms/foot). Both wires should be similar. If one is a lot higher, it won't provide enough energy to the plug under load to spark. Same holds true for the coils.
Leaking wires would tend to cause a miss in wet humid weather and not necessarily under load.
