1987 Ford Bronco Engine cranks but won't start

Hello and thank-you for reading through my question!
I have a big 1987 Ford Bronco XLT with a 351 Cleaveland engine. It has a TFI-IV ignition system and related parts.
I have had to replace the starter, alternator, coil, distributor, solenoid and even the fuel pump on the electrical system as needed over the past few years and some parts very recently.
The engine had been idling very, very low for about a week beforehand, and would stall if you took your foot off the gas pedal. Also, the solenoid and the coil would be hot, and the truck had to sit for about an hour or longer before it was cool enough to try again. The engine cranks over, but it just doesn't "catch" and start and the battery completely drains very quickly. It would start again only with a boost. Once it was started you could go and keep going, as long as you didn't let it stall at the low idle!
The coil has been replaced (used one) and so has the solenoid (new).
So now the big problem is. The truck turns over with the battery being fully charged, or with a boost from another vehicle, but the engine just will not "catch" and. Well. Go! Any suggestions? I am thinking it might be time for a new "brainbox" (EEC IV Module). And maybe a new truck! LOL!
Thanks in advance ~ Sandra ~