I’m contacting you regarding my 2019 GMC Sierra 1500 with the 5.3L V8 engine. The vehicle is currently experiencing a cylinder 8 misfire (code P0308), accompanied by engine backfiring, ticking noise, and exhaust fumes inside the cabin. Additionally, the ESC (Electronic Stability Control) warning light is on, and performance is noticeably affected. To date, I have: •Replaced all spark plugs and fuel injectors •Verified proper ignition coil function •Had an oil change on September 23, 2024, during which I reported early concerns about engine performance (shortly after the powertrain warranty expired) •Had a transmission flush on March 17, 2025, in an attempt to resolve continued drivability issues Despite these efforts, the issue persists. Given the known issues with AFM lifters and camshaft wear on this engine, I suspect a mechanical failure related to that system.