3.9L Lincoln LS Miss ... HELP

[1sicklx]

I need help diagnosing a single cylinder miss. Coil pack, spark plug, and fuel injector have all been swapped around, but miss persists on same cylinder.

At this point, I'm suspecting that an exhaust valve may be stuck partially open causing the miss fire. One thing that got me to thinking about this is that on the side that the miss is on, the exhaust pipe is actually sucking air in, while the other side is blowing exhaust out.

I'm thinking about opening it up to investigate this theory more over the weekend, but want to get some feedback first.