It all started with an engine light about a misfire for a bank in the back, replaced all 3 ignition coil packs in the back (the error code was for one of them) also replaced all 6 spark plugs. Everything was fine for a month, then I started getting a weird engine knocking at a stopped light (while in drive). When originally replacing the coil packs noticed there was a decent amount of oil on on, so in turn I replaced the valve covers and gaskets. After doing this, the mysterious engine spurts started to pick up more while the car is at idle while in drive. There isnt a service light, but the knocking almost backfiring occurs when under load at idle. If anyone has any suggestions. If anyone has any suggestions that would be great.

 

A video would be helpful

 

Clogged precat. Hook up your vehicle to OBD II scan tool to detect specific error code.