1997 Chevy Lumina P0303 - Third Cylinder Misfire Despite Replacing Ignition Coil, Spark Plug and Fuel Injector Wiring

Model: 1997 Chevy Lumina Fault Code: P0303 Posted: 2009-04-01 14:09

I've tried several solutions so far: - Replaced the ignition coil - Changed the spark plug on cylinder 3 - Replaced the fuel injector wiring harness (it was previously damaged during an intake installation) Compression is good, and the fuel injector for cylinder 3 has been tested and confirmed as functional. However, I'm still experiencing a persistent misfire in cylinder 3. The engine struggles to start and shuts off prematurely—whether or not it reaches normal operating temperature. I've ruled out basic electrical issues and mechanical problems. Any additional troubleshooting steps or diagnostic suggestions for this P0303 code on a 1997 Chevy Lumina?