Is your SES light on?? All you have to do is take a paper clip and short out the top two right terminals, and watch the SES light blink. It will blink 12 to tell you it is in fact in diagnostic mode, then it will blink the code. Then you can find out what it is. Hope this helps.
It's running well but idling rough. I thought if I take it to pep boys or some other place they might be able to tell me if I need an o2 sensor. I'm replacing the distributor cap and rotor this weekend hoping that that might help. No, there are no lights on (SES)