The customer reported the engine light was on and the vehicle was misfiring and running rough.

The engine logged multiple misfire codes affecting all cylinders. Despite ignition and fuel system components being replaced or tested, the fault persisted. The misfire counters in the ECU would record misfires without any perceptible change in engine performance, particularly when holding the engine between 2000–3000 RPM in park or while driving under light load before the engine reached operating temperature.