P0306 Fault Code on 2004 Grand Am - Cylinder 6 Too Lean After Fuel Run-Out

My 2004 Grand Am won't start after running out of fuel. Once fuel was added, the engine started but with a persistent P0306 diagnostic code indicating cylinder 6 is too lean. I tried an injector treatment, which allowed starting, but the P0306 code remains even after clearing it using an O2 sensor replacement. No drivability issues are present, but the check engine light stays on, preventing smog compliance. All spark plugs, ignition wires, and coils have been tested and show no faults. Given this, I suspect a clogged fuel injector in cylinder 6. Any advice or recommendations for further diagnosis would be greatly appreciated.