Chevrolet Repair: 97 Chevy Astro, oxygen sensors, chevy astro

Question
I have a '97 Chevy Astro with the 4.3L V6.  It idles rough and seems to be getting overloaded with fuel on idle.  The Check Engine light will come on and stays until drive on highway for a while.  According to error code, it is an Oxygen sensor (it has 4 Oxygen sensors).  At times it runs great.  I thought that if an Oxygen sensor was bad, it was bad.  We have had problems with distributor caps and rotors.  Replaced twice in 5 months.  It showed error code as mis-firing in cylinder 4 (cylinder 5 the second time).

What else would cause the rough idle and the error code for Oxygen sensor low voltage?  Is there and easy way to tell if a sensor is bad?  I don't want to replace all four sensors ($250).  Since it was intermittent, I thought it was a bad wire on a sensor, but they are ok.  THANKS for any help you can share.

Steve

Answer
Steve
If your getting this code then one sensor is bad, or maybe a few more. What I would do, is buy one 02 sensor, change it, and see if this doesnt turn the lite off and change performance. If it doesnt, then you will have to replace the 02 sensor with the old one, and move down the line ect ect,, until you hit the right sensor that is bad.. Thanks..