I feel I should put a spare TFI module in every fox mustangs glovebox. But they really need to be tested first. I've had new motorcraft ones bad right out of the box. And I do have 1 new one. Not sure if it even works....
I would test them. The quality of the TFI's has changed. There was a good thread showing them pulled apart and how the construction has changed over the years.
EDIT: here it is