2014 Sierra 5.3L misfire #4 cylinder, 42K miles

[Citrus shadow]

Have a P03004 misfire code everytime.  I changed coil, plug wire, and plug one at a time with firing cylinder next to misfiring cylinder and didn’t follow, all 3 components are good.  I think it is the injector but I was reading about how direct injection has a lot more carbon build up on the valves.  Do I have a valve issue or bad injector?   Any info or knowledge of same problem would be helpful. Thanks. 

[Colossus]

That is correct about carbon build up.  I use BG-44K to help with this.  I've had favorable results. 

[Citrus shadow]

Changed injector and still misfire on cylinder 4.  So coil, plug wire, plug, and injector are fine. Why is the cylinder still misfiring? Valves  looked to be seated and had some carbon build up but not enough to be a problem I think.  

[Citrus shadow]

Took truck to dealer and have a collapsed lifter on #4 cylinder.  Changing 8 lifters, push rod, and oiling manifold. 

[Obscenejesster]

Took truck to dealer and have a collapsed lifter on #4 cylinder.  Changing 8 lifters, push rod, and oiling manifold. 

Damn. Thank God for warrantys.

Sent from my LG-H932 using Tapatalk