2000 Ford Expedition won't stay runningv

PO1131 A Heated Exhaust Oxygen (HO2S) sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The most common cause of this code is a vacuum leak. Check all vacuum hoses especially behind the throttle body. There are hoses with 90 degree bends that crack and leak.

PO125 Deals with the engine coolant temperature. It isn't getting warm enough within a set amount of time. This can be the result of low engine coolant level, a stuck open thermostat, or a faulty coolant temperature sensor.

My concern is that the coolant temp sensor may be the cause of both codes. First check for vacuum leaks. If none are found, then you need to get a live scanner that can see what the computer / sensors are doing while the engine is running. You will need to watch the coolant temp sensor to see what it is reading.

Let me know what you find. Also, let me know if it starts at all and how it is running.