Ford Repair: Diagnose Rough Idle, air control valve, chronological time

Question
I've got a 2002 Ford Focus SE. My alternator died out, and I had it replaced by a friend of my father's who has since died. Everything charges just fine, but my idle is rough. It could be a coincidence, but I'm guessing it's related. From reading online, it seems like it could be a ground fault. How do you diagnose something like that? Do you have any other ideas? Thanks for your time!! Dave

Answer
I apologize for the delay.I need a chronological time line please. Did the rough idle start immediately after the alternator installation? If not, clean the throttle body and or the idle air control valve. You will find very detailed instructions in some of my previous posts. When you say that it is charging ok, is that an observance, or have you had the system tested? If you have not, take it to your local parts store and have them test it for free.