I have a 2006 Mustang GT with the 4.6 engine in it. My car has 147k miles on it. I had a shop replace my timing gears, chain and guides recently. After the installation and re-tune to my pre timing gear change set up my engine backfires really badly. There were absolutely no backfires prior to this change. I was receiving random misfire codes even after replacing the coil packs and spark plugs. This occurs when the car is driving down the road under a small accelereation with rpms in the...

Engine backfires under acceleration