rockauto.com will before friend on cheap replacement parts.

those o/2 sensor are pretty easy to change soak them down pretty good the night before with some PB Blast a few times and again a few minutes before your ready to pull them off and should aid in getting them off easier. Some times they do weld them selves into the exhaust from all the heat cycling going on. Also check to make sure you don't have cracked manifolds the 3.8 mani's crack pretty easy. YOur window could be a couple things the contact on the switch maybe dirty or worn so its not getting good connection or the motor needs replaced being the driver side it could be any of the above start with the cheap and easy which is pulling the switch and trying to clean it i havn't had a gen 3 switch apart but on the gen 1's they have copper contacts that you can solder to fill the gap that gets worn into them from use.

SLow start is more that likly your battery, also do a tune up on it that should clear up the rough idle, along with doing that o/2 sensor.