why is my van running rough after replacing the EGR valve

also a whine/hissing noise near or from air ccompressor under hood will this effect future performance , right now truck is running great, only check engine light is on

Motor 5.4 Triton

located under van under side doors

Runs good for about 10 minutes, then starts misfire

I have already pulled the drive shaft and drum off/I see the shoes but do not see how to remove them

started unit made a noise found #7 intake rocker broken,Checked pushrod ok . starter and now have a tick at higher rpm, can you remove head in van, or best way to pull motor