I think that P0170 is the effect of your fault, if you have a misfire, then allot of oxygen will be measured down the exhaust pipe, this is why frame data and fuel trims should be looked at to see if it was try to add fuel or reduce it. Also ever time you erase the fault code, trims will revert to 0. so make sure you get all the info before erasing. You might find your self having to drive this through its drive cycles and recording data. Don't think sending it to dealer they will find it quickly if at all, this kind of fault is going to take a little time.