Can't bleed air out of rear brakes

So...all of my problems pointed to a vacuum leak. Yet there were none to be found. EXCEPT it seems that I had a small leak inside the power brake booster...replaced with the expensive auto zone brake booster, a NEW master cylinder from Napa and, vavoom, she's all better now!

Runs like a charm. No more miss on the #6 cylinder, no more rough idle, and, hopefully, no more overheating under load...

W00t!