If you removed the O2 sensor from the exhaust, and didn't turn it off in the ECU, then it will throw a CEL. It can be turned off with TuneECU and TuneBoy. I suspect that the Fuel Sensor malfunction could be cleared and it probably wouldn't come on again, but if it did then I would suspect the wiring. I would check the connections and that there is no bare wire where the insulation has worn because it had worn against something.
I am still betting that the sticking throttle is because something in the linkages has broken or there is a foreign object in there.