Truck was running great until I got a p0420 I was going to leave it but ended up replacing the cat with an aftermarket one,since than I’ve had the check engine light on solid and blinking during misfire ,I’ve been having a horrible misfire a few times a day usually on start,meaning once truck is driving good it won’t happen again until the is shut off and restarted,once it happens when I try accelerating it sounds like a popcorn machine and there’s a terrible smell maybe fuel and doesn’t allow acceleration,until it breaks free and I’m good to go,I’ve replaced injectors spark plugs throttle body etc nothing seems to be helping any advice is appreciated