[Red z]

I have a 2012 5.3 idle is rough it has a hundred and sixty thousand miles . Sluggish on takeoff. The plugs and wires were replaced at one hundred thousand . Check engine light comes and goes off after a couple days . It says misfire # 7 replaced plug still doing the same thing . Any suggestions?

 

[B52Bombardier1]

Could be a coil pack. Try a crank position relearn and try a new spark plug in #7. I did a lot of things in a similar situation as you and in the end, it was the dead last possible thing, a bad PCM.

Rick

 

[swathdiver]

Pull the spark plug and inspect it, maybe do a compression test and leak down. Probably a failing lifter or some other valvetrain woe.

 

[RedSLEd]

^^^^ this. Any tapping, knocking sounds. #7 is an AFM cylinder.

 

[spaddman]

Maybe try swapping coils, the misfire may follow the coil. If not, at least that has been eliminated as cause.