02 3.8 caravan Misfire

Hello all! Just wanted to hear some opinions on a problem with my van. Its a 2002 Dodge Grand Caravan ES with the big 3.8 v6. Had the van since new and it only has 59k miles on it, its been great and I love it! :thumb: However its run into some problems recently, I have a scanner and pulled 2 codes
P0135: 02 heater circuit (bank 1, Sensor 1)
The original sensor is on the van right now, would putting a new sensor on solve this problem? Also to note I get pretty low gas mileage and I keep up on maintenance such as air filter, cleaning throttle body, tune up etc..

P0306: Cylinder 6 Misfire detected
The van got new plugs and wires last summer, it is not a horrible misfire like its not bucking all over like a mechanical bull haha but if I put my hand by the tailpipe, the exhaust comes out a little uneven so something is up. I pulled the plug on cyl 6 and it looks to be ok, today I moved the plug from #6 to a different cyl to see if the code pops up again but on a different cyl this time. Any ideas what commonly causes misfires on these engines?

Hopefully I can get this all figured out soon because it has to pass NY state emissions inspection in a month. Safety is all good, I just replaced front brake pads and rotors and the tires have tread on them, oil changed etc I take good care of it! All the best - Anthony