Can anyone recommend a good (preferably inexpensive) Ford OBD2 code reader? It's probably an O2 sensor since I have never ever replaced one. But its probably best to actually look and see.
On the plus side, note that my odometer is still working just fine after my fix I talked about over six months ago.
...and yes, before you tell me to reset it via battery disconnect -- that's already been done. The light is off, but from the rough idle, I can guarantee it will be back on soon.
[Later edit]: Exploring the various forums shows that an extremely common problem is a vacuum leak in the PCV hose routing. On examining this, it appears one of the multitude of little rubber elbows is snotty and collapsed, while the others are old and cracked. Forum complaints are that this type of vacuum leak throws all sorts of conflicting, confusing error codes. So even if this is an O2 sensor, I'm going to replace the snotty bits before I even begin.