HELP P0154 O2 Sensor Circuit No Activity Detected

I recently installed long tube headers along with a ORY and Magnaflow catback on my 99 firebird formula. I also had the computer tuned by frost who deleted the rear O2s, Air, and EGR. I got everything hooked back up with the O2 extensions and I keep getting O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)
SES code. I checked all of the connections on my first ( AC Delco AFS 98) O2 sensor and noticed that there were two wires disconnected from my wiring job. Re connected everything and still getting the code after driving a couple miles. I removed this O2 sensor and used one of the Rear O2's (AC Delco AFS 97) and this one worked for around 60 miles until the plug got disconnected from the harness in this recent flooding going on in RI. Because i was dragging the connector through three feet of water i assumed that it would be shorted but tryed reconnecting it anyways. Plugged it back in worked for around 10 miles and P0154 SES code came on. Yesterday i removed that o2 sensor and used my last sensor that came off my car before the install (AC Delco AFS 98) drove 10 more miles today and the SES light came on again. I am really puzzled here. I have no idea what the problem is. I tried three different sensors and the only one that i have minor luck with was AFS97 which is the correct senosr for the passenger side header. I was told that the only difference between the sensor numbers is the length. Beacuse i have to extend them anyways it should not matter. I checked the fuses and everything appears to be okay. The only other thing i can think of is that i have the passesnger header plugged into the rear O2 harness. Can anyone specify the locations of the header and rear O2 sensors on the passengers side? Any other ideas would be helpful. Thanks

both front O2 sensors plug into connectors that are right on the K-member near the engine oil pan.
Also O2 extensions are sometimes problematic. The best solution is to use the Bosch 13111 O2 sensor. It has really long wiring (no need for extensions) and tends to be more reliable then extensions. If you go to a parts store and they don't know what you mean when you ask for a Bosch 13111, then ask for a rear O2 sensor for a 2001 Corvette.