That back stud is definitely broken and needs replacing; hopefully an easy out will take the broken piece out for ya. You can see that exhaust gases are leaking out at that port as shown by the black on your cylinder head. Like weed said, it very well could be sucking in air and throwing o2 faults

 

Ok, thanks guys. Yes, those studs are definitely broken. I didn't realize they were also keeping the manifold on and sealed. I will move on to that and post back.