Would the ecu detect a bad TFI Module/Coil?

I was wondering the same thing. Will the ECU detect any problems with the TFI? Or do TFI problems just never show up as any codes at all?

A bad TFI or coil will NOT throw a code unless they cause a misfire. If the engine just stalls and won't start, no code.

A bad TFI is almost always heat related. The car will probably start out running good in the morning, then as the day goes on and the temps get hotter, the car will start running bad, missing cutting out, dying, etc. Let the car cool off and restart, and it will probably run good again until the pattern returns, but it will get progressively worse and worse. Heat soak is the reason the TFI was moved on later years. I'm not aware of any code it will throw.

Sounds like you may be starving for fuel. Replace the fuel filter and consider a new fuel pump if it's older.

BlackGT89 said:

A bad TFI is almost always heat related. The car will probably start out running good in the morning, then as the day goes on and the temps get hotter, the car will start running bad, missing cutting out, dying, etc. Let the car cool off and restart, and it will probably run good again until the pattern returns, but it will get progressively worse and worse. Heat soak is the reason the TFI was moved on later years.

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That's right. On Foxes, TFI failures are usually caused by chronic heat soaking and indeed that's why the TFI was moved to the passenger side inner fender on SN95's. Ford also added a heat sink.
That seems to have solved the heat soak related failure but it didn't stop mine dying last week. It happened as I was driving to work and the engine was still cold. It stalled in exactly the same manner as when my PIP sensor failed last year, with the rev counter dropping to zero as if the power was suddenly cut. I managed to get it going a couple of minutes later and made it to work. In the afternoon when I was driving home, the engine died again but wouldn't restart for love or money so I needed a recovery vehicle to scoop the car off the road. A new TFI module fixed it. I can't complain though 'cause the original one lasted 15 years, and the original PIP sensor lasted 14.
I added my own little story just to show that you'll get little or no warning of when the TFI is about to die, unlike the PIP sensor which takes a few weeks to die completely. This might help differentiate between the two when trying to diagnose the problem but practically speaking, if one dies you can be sure that the other will soon follow so it's better to replace both at the same time.

The ECM may not throw a code that specifies as a TFI code. But it will throw certain codes that can lead you in the direction to have the TFI checked, as well as the PIP sensor. But only from certain circuits. These codes are only logged in the Continuous Memory codes. And even if one of these codes are not thrown, it still doesn't count out the TFI or PIP sensor as being faulty.