Welcome to the forum.
1994 was the last year for distributor in the 3.0l Vulcan engine.
So the last year for the TFI Module on the side of the distributor.
TFI module runs the spark, and they were well known for becoming temperature sensitive as they got older.
You mentioned replacing ignition control module(ICM), which you don't have on a '94 3.0l.
TFI module could technically be called an ICM but isn't.
An ICM did need/use a crankshaft position sensor because there was no distributor, and an ICM controlled a coil pack, multiple coils.
TFI system just used the 1 coil and no need for cam or crank sensors because of the distributor.
So you replaced the TFI module?
The TFI module does send the computer a timing pulse, PIP, so computer can time the fuel injectors.
But you should get a CEL(check engine light) if this pulse stopped or was erratic.
I would try to get the OBD1 codes from the computer yourself, not hard to do just count the flashing CEL to get the code numbers.
Video here on how to do that: www.youtube.com/watch?v=X07hu0kAuzE
1994 will be 3 digit code numbers, found here: OBD-I Diagnostic Trouble Code (DTC) Applications - Ford 3-Digit Codes
If there are no codes, not even the 111 for "all good" or they can not be retrieved then you could have a computer problem which is why it has been hard to diagnose.
Computers rarely fail so I would put my money on a wiring issue.
Start engine and start moving wires around, see if you can cause a stall
The fact that it restarted using Ether, could mean weak spark or low fuel pressure