DTC P0171 - If the average long term fuel trim value is above 20 percent, this DTC will set. I would try replacing the heated oxygen sensor (HO2S). The symptoms point to a possible faulty 02 sensor.
Could not find a DTC P0463, but did find DTC 0453 - This is related to fuel tank pressure sensor (FTP) for detecting vacum decay. The DTC is set when fuel tank pressure sensor voltage is > 4.9 volts.
Not sure if the Techroline would have adverse affects, but you never know. I'd run the tank empty then clear those DTC'*.