Bad O2 Sensor?
 

Hey guys! Have a good one for you. I have a 1994 w124 sedan, love it! had a problem with the driverside power seat, SRS light on and the usual surging at idle. Because of the weather here in the midwest I haven't had the time or temp to work on her, but now that the weather has been getting better I have started to work on her. In the meantime the surging has been getting worse. Did the usual, repaired/ replaced the engine wiring harness, mass airflow sensor, O2 sensor, engine temp sensor. Checked for vacuum leaks with brake cleaner, replaced 2 hoses. My independent MB tech checked for codes and every time he clears the codes, after a day of driving, the same codes come back! Idle stop, lean fuel mix right bank/left bank, bad O2, bad lambada. This morning I checked the O2 wires in the car under the pass floor carpet and on every wire (all 4) I get ground. I thought that on start up I should get 12v on one of them for the heater or am I wrong? Could all by electrical problems be connected? I know that you have all talked about this about 100 times before and I have looked in past treads but I can't figure this out and my friend is VERY BUSY and I don't want to take up all his time, if at all I would like to fix this on my own. Thanks in advance for everyones help!