Mopar does not like you to solder the 02 connector wires unless its up above the connector in the harness side by about at least an inch or more. The 02 sensor actually draws a small amout of outside air thru the wires to compare it to the air (02) in the exhaust. It does that right at the connector so if you go a good inch or more above it the sensor should still work as long as you have a good clean solder and its good to use the heat shrink with the sealer in it as that seals up real good.
Also on mopars from about 2000 and newer the downstream 02 does more then just give the PCM a reading to compare to the upstream 02 and see how the converter is working. It also uses the downstream 02 sensor reading to set the goal of the upstream 02 sensor. The goal is the switching point from lean to rich which is normaqlly .5 volts but if the PCM sees the downstream 02 hanging say more rich then it should it can change the upstreams switching point (goal) as if it sees it rich to long it will drive the goal to a slightly lower voltage an moniter it to see how it does after that. In other words the 02 normally has to go just below .5 to switch from rich to lean but if it drives the goal down to about say .4 volts then the PCM will be driving the fuel mixture lean longer as its above .5 it sees rich and is driving the fuel lean and with the lower goal it wont switch back at .5 but will keep driving it lean until the volts drops to .4 and that will help if its seeing to rich a reading for to long. The same goes if it sees to lean as it will raise the voltage some. It also takes into account the adaptive fuel cells its in.
Also somewhere around 2005 or so Mopar changed the 02 voltage readings as the raised the voltage reading to read from 2.5 to 3.5. They did this by biasing 2.5 volts on the ground side. It gives less chance of small resistance causing voltage problems and bad readings. You just have to remember on the ones like that the 02 just reads from 2.5 to 3.5 instead of 0 to 1 volt. Ron