Electronic Ignition System Diagnosis
WARNING: This page is about a different car, the 2003 GMC Savana and 2003 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
See DISTRIBUTOR IGNITION SYSTEM under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.3L CHEVY EXPRESS & SAVANA article.