I had posted a question about intermittently losing spark on my 1985 pickup a while ago. It has EFI and the thick film ignition system. I finally figured out what was wrong. Here are the steps that I took to diagnose the problem.
1) - The engine was intermittently quitting while driving. Finally it quit completely and I towed the old girl home. All KOEO tests run fine, PIP was latched in mem codes though.
2) - Tried changing the TFM, no help. Checked power going to the distributor, fine. Checked that there was a pulse going to the coil. Pulses fine. Tried to start the truck and it started fine. --???--
3) - Ran it for a while and it quit on it's own. Nice, now I can diagnose it. It would run for a few minutes and then die. Connected a DVM to the minus of the coil (AC volts setting). Appears that the signal is going away when it dies. Hmmm cause or effect?? don't know.
4) - Connected DVM to PIP out, it goes away too. Checked power and gnd again, looks fine, no changes when it dies.
5) - O.K. heavy artillary time. Took out my old 40 Mhz O-Scope and connected it to the PIP and the tach signak (coil minus side). Both signals go away when it quits.
6) - Changed out the Hall effect pickup in the distributor (thinking it should be the only thing that will cause both PIP and Coil to go away if power is good). Found corrosion in the hall effect pickup. I'm thinking I have it solved. She runs good now..
7) - After a week it quits again. Got it back home and reconnected the O-scope. Now PIP stays, but Minus side of coil goes away. Traced the wires and found a connection to the coil that was corroded right off. The bad connection was right around the 2.2K resistor. Found that this 2.2K resistor is used by the EEC to make sure that the coil gets fired, so it should run without it. I confirmed that by disconnecting it. The truck ran fine, but threw codes (sorry I forget what codes, but it was pretty self explanitory). Fixed the connection to the coil and it runs for another week then starts dieing again. Much yelling, drinking, and crying. My wife and kids are scared I might jump off a bridge or something..
8) - Found that when it died if I left everything alone, I could hear the fuel pump kick in after a few seconds. Tried the fuel pump and EEC relays, no luck. I was wiggling the wires over on the passenger fender and found that the fuel pump would kick in and out. After poking around for another day I found that the main power feed to the EEC/fuse panel was corroded right off.
9) - I inspected all the wiring connections under the hood and replaced anything that looked suspicious. She's been running fine for a couple of months now!! A difficult diagnostic adventure because there were multiple problems. Very frustrating, but I learned way more than I ever thought I would need to in the process..

Moral of the story and things I learned:
The TFM only needs power and gnd to generate the PIP and tach signals. The SPOUT and 22K resistor circuits can be missing and the vehicle will still run. The EEC gets it's crank position info from the TFM PIP signal (via the hall effect device in the distributor). If you hotwire the ignition, it might not run if there is another power issue, because the EEC needs to be powered up to sense the crank position and generate the necessary pulses on the fuel injectors. This makes the ignition and fuel system have a single point of failure that can be difficult to separate out. Make sure that the codes run clean. I found another broken wire going to the temp sensor and the codes reported it accurately. Make sure that if you have one of these older trucks that has lived a long time in a salty environment that you double check the connections. Use good solder to fix the bad connections and make sure that you clean any flux off before you finish the job. Some of the bad connections I found were one's that I had fixed many years ago. I'm pretty sure that the flux reacted with the elements and accelerated the breakdown. I should have know better since flux is an acid and should always to be cleaned off.
I sincerely hope this helps someone else out there with an old Ford truck!!
Peace
mb