1998 GM 3.1L Engine P0304 Misfire - No Spark or Compression Diagnosis

Model: 98 GM 3.1 Fault Code: P0304 Posted: 2015-10-26 16:02

I've been troubleshooting a persistent misfire on cylinder 4 in my 1998 GM 3.1L engine, showing fault code P0304. I've already replaced all spark plugs, ignition wires, and coil packs. After swapping the coil pack positions, the issue still persists specifically with cylinder 4. The EGR system has been tested and is functioning properly. Spark is confirmed at cylinder 4, and vacuum tests show no leaks. Despite extensive checks over the past year, I'm unable to identify the root cause. Any insights into potential issues like a faulty injector or low compression would be greatly appreciated.