Chevy trailblazer P0300

Chevy Trailblazer

Read obd reader P0300 changed out 6 spark plugs to brand new found one coil that looked corroded, unplugged that coil to see if engine ran worse. No change in sound so I figured this cylinder is definitely the problem, changed that coil cleaned throttle body. Still getting same issue changed fuel filter fuel pressure is good. I feel I’ve isolated the problem to cylinder 4 which had corrosion but now am wondering what it could be

Could be a bad fuel injector. Try swapping it with a different cylinder and see if the problem follows the injector.
P0300 Chevrolet – Cylinder Misfire Detected Random Cylinders

Possible causes
– Faulty spark plug (s)
– Faulty ignition coil (s)
– Clogged or faulty fuel injector (s)
– Intake air leak
– Fuel injectors harness is open or shorted
– Fuel Injectors circuit poor electrical connection
– Ignition coils harness is open or shorted
– Ignition coils circuit poor electrical connection
– Insufficient cylinders compression
– Incorrect fuel pressure