Check our battery condition then. Low battery charge can cause miss fires as if you have electronic ignition it take a minimum of just over 12 to maintain constant ignition. Check you terminal condition and your grounds. Make sure terminals a shiney clean (both post and clamp) and tight. As for plug wires it is not always the terminals that are the culprit but they 'braided' conductor inside the insulation that deteriorates or gets stretched out of shape.