This Sensor is located on the Exhaust system just after the manifold since your vehicle is V8 so you got to know which side is bank 1 on your vehicle, most of the time bank 1 is on lift side if you facing the engine from front......................Now you need to check the sensor heater circuit for resistance between two pins on the sensor and power and earth on its plug before you replace with new one...........Here are some links where you will get some idea.............


https://www.youtube.com/watch?v=LbllLITzh04

http://easyautodiagnostics.com/ford/4.2L/oxygen-sensor-heater-tests-1

https://www.youtube.com/watch?v=kRKki3COMOc