2001 Chevy Silverado 4.3L Misfire - Persistent Cylinder 4 Misfire Despite Full OEM Replacement of All Components

Model: 2001 Chevy Silverado 4.3L Fault Code: P0300 Posted: 2011-03-24 18:38

Experiencing a persistent misfire on cylinder 4 in my 2001 Chevrolet Silverado 4.3L engine. I have already replaced all major components including: - Spark plugs - Ignition wires - Distributor cap and rotor - Four oxygen sensors - Y-pipe and catalytic converter - Upper and lower intake manifold gaskets - MFI fuel injector system All parts are OEM quality. The engine runs smoothly, starts easily, maintains steady vacuum pressure, and compression readings across all cylinders are consistent at 135–140 psi. Despite these replacements, the OBD2 misfire code (specifically cylinder 4) persists. The vehicle currently fails emissions inspection. The distributor gear appears in good condition, and spark plugs show signs of lean combustion. I have tried using scan tools for diagnostics but they are unable to provide meaningful trouble-shooting insights. Seeking local expert help in Ithaca, NY, to identify the root cause. Any experienced mechanics or technicians familiar with 2001 Chevy Silverado 4.3L issues would be greatly appreciated. Thanks, Tom