Remove the spark plug caps, disconnect the ignition cable from the distributor cap and ignition coil.
Caution: When doing this, pull on the plug, not on the cable.
Connect an ohmmeter and measure the resistance.
If the resistance is too high, clean the cable connection points and repeat the measurements, otherwise replace the cable.
Check the insulation of the ignition wires by bending the cables in the area of the spark plug tips and checking for breaks, otherwise replace the ignition cable.
Check the distributor runner.
Connect the ground cable to the battery.