[72timemachine]

Thanks for the information. His truck was skipping a while back so I replaced the rotor, the cap still looked good so I just shined it up a little with some fine sandpaper and the skipping went away.

Not sure if this is true but someone told me the gap will grow over time between the rotor and the cap, thus causing a skip. The tip of the rotor wears enough to creating a larger gap for the spark to jump across. Seems to make some sense.