High resistance plug "wires" can be a source for an intermittent miss. The carbon impregnated string conductors that most ignition systems run instead of metal core wire can break down and fail to flow enough current for a good spark. Use an ohmmeter to check each plug wire, and replace them if you find more than 1 K-ohm per inch. For instance, a 12" long plug wire can have up to a maximum of 12K ohms, etc. Most wires will have less than half that much resistance, but don't get tempted to run metal core wires- - - -they can cause rapid erosion of distributor cap terminals and rotor tips. A yellow or orange looking spark is OK- - - -the "hot blue spark" we're used to looking for hasn't been there for a few decades, even on very high voltage ignition systems.
Jerry
