Visual Inspection
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure harness connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see appropriate VACUUM DIAGRAMS article to verify routing and connections. Check air induction system for possible vacuum leaks.