Each sensor has a operating range they operate under. Get a voltage meter and see what voltages the sensors are reading then compare this to what they should be showing. If this is a PRE 96 car then I would look up winaldl and make an aldl cable.
If you take your car to an Autozone they can place your car on a diagnostic and it will give you all of the trouble codes with the car if you have any bad sensors.
In order to diagnose sensor problems for your Thunderfird I would put the car through a series of intense testing. Once the car has been put through many types of testing you should be able to find a problem is there is one.
