I've had my car for about 4 months, I got a rough idle. And engine codes of a random misfire in all my cylinders. Also noticed smoke from underneath when rev, my engine possibly the Cat, but I'm unsure, my acceleration in the car takes way too long and when in 5th gear, it doesnt as up as much stays around the same mph, and wont go past 110mph, I haven't changed the head gasket yet, or timing. If anyone can help with this it helps me figure it out,