Well I trust the mecanic as he is a friend of ours. He hooked up his OBD reader, and said that both sensors (new and old one) seamed to be running the way they should. He just fiqured the old one could have been a worn out so it could be the cause. I don't think it's the senor in itself but the wireing harness going to the sensor might be the cause.
I ran across this on a different site.
"Oxygen Sensor Problem
On some 1995-1996 LH cars, the Malfunction Indicator Lamp may come on, and be accompanied by a possible sag or hesitation or rough idle problem. When you hook up a scan tool, you may find codes that indicate the right or left upstream O2 sensor is shorted to voltage. The cure here is not to replace the sensors, says Chrysler technical service bulletin 08-13-99, but to install a special jumper wire harness to correct the broken splice in the wiring harness. Ignition"
I know mine is not a 95 or 96 LH, but does this seam relevent to what my car is doing. Minus the rough idle that my car does not seam to have.
It is a Chrysler 3.5L OHC V6 Engine Service Bulletin
Saturday, August 18th, 2007 AT 7:21 PM