Shut off while driving, engine cranks but no fire?

Hello, sorry to hear about your issue here. But with no check engine light, that is a sign the engine computer is not being powered up, have you checked all the grounds on the vehicle, even the frame to body grounds and engine block grounds, since the ECM will usually be grounded to the block. I'll pull the wiring diagrams for the ECM power and the ground diagrams for you, you could probably put the old computer back on until we find a reason it's not powering up. It's good to have the original computer on the vehicle if it hasn't actually failed.

And do you have power to all the fuses in the engine compartment fuse box? Id would check them with a test light and a multimeter to make sure there is full battery power to each fuse since they all have a direct connection to the battery in that fuse box. I'm getting the wiring diagrams for the PCM together for you, powers and grounds. The grounds for the PCM do go to the engine block, so does Battery Negative, the PCM has at least 4 or 5 grounds I see so far, they look like they're all black wires with a White stripe. G123 is Ground at the Rear of Engine Compartment, which is also where the Battery Negative wire goes.

Here are some guides to help. I will post the diagrams next.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Sorry for the delay, some of the aftermarket diagrams were incorrect, so these are the OEM Ford diagrams. Diagram 1, 2 are the PCM ground locations.
Diagrams 3, 4, 5 are for the PCM Connector so you can check for power and ground right at the connector, hope fully it's not too confusing, you just need to concentrate on the 6 Grounds and the 3 Power feeds to the PCM. D
Diagram 6 is for the PCM power relay, if you take the relay out of its location, out of the 4 pins where the relay sits, 2 pins should have power at all times, and 1 pin should go directly to ground. So, if you use a multimeter to check for power here, just touch the pins lightly without pushing the meter leads into the pins, that will spread the pins and the relay will not make good contact afterwards.

Something else you should check is the 3 sensors in diagram 7, marked in Green on that sheet as well as the PCM connector sheet. Those 3 sensors use a 5volt Reference, and if one of those sensors shorts out and pulls the 5volts down to ground, it will disable to the PCM and can act the same as if the PCM was not powered up, So if you find power and ground where it should be at the PCM connector, unplug one of these three wire sensors and check for a 5volt feed on one of the wires, the throttle position sensor is the easiest to check, you're just looking for missing voltage here with the key On. If it's missing, unplug the next one. If the 5-volts is not missing when one specific 3 wire sensor is unplugged, check for a Check engine light, you may have to cycle the key.

The trick here is if one sensor is pulling the 5volts to ground, and you unplug it, the issue is no longer there, so not effecting the other two sensors at that point, but plugged back in and the issue is back, this is where you would have to back probe the connector with a pin and see if that specific sensor is bringing down that reference voltage.
It may sound confusing, but the idea is checking the sensor while plugged back in to see if the 5-volts is there or not.
A shorted sensor causing the computer to go down is common but can be difficult to find. Thankfully there are only 3 sensors on this truck that use that 5volt Ref.
The last diagram is the aftermarket PCM connector just in case. Sorry for the long post.

You want to check for voltage at the PCM connector on the 3 wires that I marked on Red, and the 6 Grounds marked in black. The Coil pack is controlled by the PCM, it has 4 wires to it, one wire is power, the other 3 wires are control for each coil. The coils are ground side switched, and one coil sends spark to 2 cylinders, it's known as a waste spark system. But with the key On, you should see the Check engine light come on for at least a few seconds. You can also look at your Tachometer, if you have lost a crank sensor signal, the tach won't move at all when cranking. But you should see a check engine light, that's why I mentioned checking the powers and grounds for the PCM. But remember if one of those 3 wire sensors shorts out, it will have the same effect. It can cause the PCM to go down.

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Sorry the delay, working nights due to the heat down here. Be sure to check under the truck as well for any braided frame to body grounds, they can have high voltage drop across them, even if they look okay, run a large temporary ground and see if it starts.

Okay, unplug the throttle position sensor and with the key On, see if you have 5-volts on one of its wires as well.

Okay, I will usually load test the powers and grounds to make sure they can carry current, I'll use a turn signal bulb most of the time, they pull a few amps, but for now see if you have a 5volt reference on the throttle position sensor. Out of the 3 wires one will read 5volts with the key On. If the 5volts is missing, plug the TPS back in and recheck at the Differential Pressure Feedback (DPFE) Sensor on the EGR valve for a 5volt reference. Let's see if this is a sensor issue.
Another quick test to rule out any bad engine or body grounds is to run your own grounds for testing purposes, you can use some jumper cables, just connect to battery negative, to the engine block, and to the body/frame. That way you're grounding the entire vehicle, it's good to use jumper cables for this since they can carry high current loads. If you ground everything out, and it starts or at least the Check engine light comes back, you know your dealing with a bad ground.
You can even hook a test light to Battery negative and touch the block, a bad ground will light the test light, but try the jumper cable method since its quick.

I assume the check engine light would work prior to this issue? Its not burned out or anything I hope.

Sounds good.

Is your battery in good shape, can you test the volts at the battery?