Hi all. New to this forum, but not to Saturn or mechanical issues. I have a 2000 LS2 3.0L V-6 that has a running problem. Was running fine but after the service light came on, the fuel economy dropped and it would hesitate on acceleration. It had a code for heated O2 sensor circuit failure on bank 1 sensor 1. To be sure it was the sensor and not the wiring or other problems, I switched the sensors between bank 1 & 2. The code then gave me the same code for bank 2. I switched them back and cleared the codes, and replaced both upstream sensors, banks 1 & 2. Now it runs fine for about 50-75 miles, then the service light comes back on and gives me a code for running lean on bank 2. Says possible air leak or sensor, bank 2 sensor 1. When I replaced the sensors, I torqued them to 33 pounds as recommended. Could I have gotten a defective sensor, or does anyone have another idea for me to consider and check first? Also, does anyone have a wiring diagram showing or giving the wire colors and functions for these 5 wire oxygen sensors? I do have most any tool I may need and can test the sensors, but prefer to know the correct wiring first to avoid potential problems. Thanks in advance for any help.