Well a PO171 usually means system to lean, could mean 02 censor like you said, mine (its a Zetec) was a vacuum leak. So what I would do is get a new alternator then if that doesen't work, (wait you gettin a battery light too didn't notice in the post, could be a system to lean problem with the stuttering) this is a good question, mine when it had the vacuum leak, it just stuttered with no electrical problems. If your having problems with your lights and such, I'd say your running lean and need the alternator.
And also the post wasen't too long, I've seen worse.
