Note On Intermittents
WARNING: This page is about a different car, the 1995 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
With engine running, manipulate affected wiring. If fault is induced, code will set and wiring should be repaired for intermittent open or short to ground. Disconnect and reconnect distributor connector and PCM connector, ensuring they are latched.