Ford Explorer 97

Well! That what I found. Welcome to any one who can add more information Thank.
The fuel trim, both long-term and short-term, refers to the changes the ECU is making to the fuel delivery. Severe negative fuel trim indicates
that the ECU is commanding the fuel delivery lean, presumably to compensate for a rich runing condition. Without getting into excessive
detail, the most significant aspect of severe negative fuel trim is that the ECU knows there is a rich condition, and is attempting to correct
it, as opposed to a rich condition commanded by the ECU. With the ECU
attempting to correct for a rich condition, you should suspect mechanical component failures, such as fuel injectors, fuel pressure regulators, etc., as opposed to sensor failures such as bad O2 Sensors,
Temperature Sensors, etc..