Hi Charlie! Nice to make your acquaintance! I just checked over at RockAuto and they list one. You could contact Jerry at jerry's gaskets or Kurt White at White Racing to check to see if they have any NOS on the sensor.
Humor me for a moment, even tho I'm a bit eccentric. This sensor is an electro magnet and a reluctor wheel. I would pull the sensor from the head and check the face for sludge or dirt or anything that could weaken the magnetic field. Okay that's just me because I don't understand how an electro magnet breaks, sorry.
Now mind the spacer that I think should be present to keep the correct gap between the magnet and the wheel.
Also, if you decide to ohm out the injectors using the ECM main harness plugs be aware that you can/should not use the probes from your VOM directly into the harness plug cavities. Those probes are just a bit too big to fit into the female terminals with out distorting them. You don't want that to happen. I'd use some phone wire to probe the cavities and then touch the VOM probes to the wire. If you spread those terminals even a bit you get an intermittent contact at the harness plug and it drove a member crazy with weird symptoms. Search threads under "TCrabs" to find his story. I just related the short version.
On another note. Is there another brother near you that would be willing to let you use their ECM. I had one of my ECM's go bad and give me a DTC61 and after pulling the plenum to check all the electricl aspects of the flow chart I found it to be the ECM and not any parts on the motor. Just bear that in mind. I don't have my FSM handy to look over the DTC diagnostic chart for #31 so I don't know if the ECM is listed as a suspect.
Tom