Where is the CID sensor located on a 1994 Explorer 4.0 liter engine?

The 1994 Ford Explorer 4.0L engine doesn't have a component specifically called a "CID sensor." There's no sensor with that name in the Ford's nomenclature for that year and engine.

You might be thinking of a different sensor. To help you find what you're looking for, please clarify what you're trying to measure or what the sensor's function is (e.g., crankshaft position sensor, camshaft position sensor, coolant temperature sensor, etc.). Providing more context about why you need to locate this sensor will allow for a more accurate response.