Diagnostic Aids
WARNING: This page is about a different car, the 2002 Pontiac Sunfire and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
An intermittent can also be the result of a defective reluctor wheel. Remove the crankshaft sensor and inspect the reluctor wheel through the sensor mount hole. Inspect for porosity and the general condition of the wheel.
Verify that the Ignition Control (IC) module ground circuit has less than 0.5 ohms resistance.