6.7 Rough Idle/Misfire

[emanmx11]

Ive got a 2011 6.7 with 220k miles on it. It had a high idle injector knock, and a misfire in cylinder 4 so I replaced the injector and that took care of the knock, but it still has a misfire in that cylinder. When i bought it the glow plug in cylinder 4 was also missing, so Ive also replaced the glowplug in that cylinder. At this point I'm hoping theres not a broken valve or a glow plug tip bouncing around in the cylinder but I figured I would hear it. Theres also a very distinct air pulsing sound at idle, and when you put it in drive and stage it up in place, the pulsing sound gets very dominant, especially with the intake cover off. Any ideas?

 

[SEABEE08FX4]

Do a compression test on that cylinder.