You said it's rich so it could be a few things, check TPS voltage, check all vacuum lines for a leak, if it idles ruf check the plugs and wires. Try pulling each plug wire out while the car is idling to see if it changes when removed from plugs. If it doesn't you may have found your problem cause it should immediately run worst when removed from that cylinder. If all of this fails, swap ecu's with one of your locals and see if it clears it up. Report back and let us know what you find.