The spark plug wires should be physically inspected in a darkened garage that has ventilation with the engine running. Turn the engine on and notice each plug wire arcing or giving small sparks at any point of damage and note down to replace it with a new one where needed after which engine should be left to cool and the distributor cap and rotor checked. Open and unscrew the screws holding the distributor cap and remove the cap. Examine the top of the cap in regard to cracks and corrosion in the contacts, and remove any deposits on the contacts with a fine file. Should damage be detected, mark that a replacement is necessary and inspect rotor at best seen at the top of distributor shaft and attached with two screws. Take out the screws, examine the rotor to identify cracks, and examine the metal contact with regard to excessive burning and pitting, indicating the need to change the rotor. Check centrifugal advance assembly to verify that there are no damage and that it moves freely lubricating the contact points with silicone grease. In case the rotor and cap are found in condition, put them back in place; when the cap will need replacement, leave that off, but leave the wires attached. Test the spark plug wires more by removing them individually, unwinding them out of the spark plug either with a removal tool or by peeling the rubber boot. Check the inside of the boot to make sure there is no corrosion, that the plug fits loosely into the end of the spark plug, and it crimps the metal connector. Wipe all the wires with a rag, looking at both ends of them, to see whether they are burned or cracked, and bend the wires, so that the conductive part of the wire within them has not hardened. Repeat on the distribution cap to make sure that all the wires are well in place on both ends. In case the cap and rotor are in a good condition, reconnect the battery cable. In case of necessity of new wires, take them along with a new cap and a new rotor. In case of installation of new wires, install them sequentially so that they will be in the right firing order and connect the cap to the distributor and reconnect the battery cable.