I beleve tha tO2 sensors are analog. and therefore a bad wiring job will affect the "calibration" of the sensor and results in incorrect readings. If the output from the sensor to the ECU falls outside a normal range of values. The ECU does a "Scooby Doo" and goes "WI Won't Woo". And runs in Limp Mode to Failsafe Mode which means the engine will run...but run like shit.