No spark - engine doesn't start

Hello,

I have a 1988 Chrysler Le Baron 2, 2 turbo cabrio and I already bought it broken (thought it was gonna be easy to fix it and enjoy the car) and I have no more ideas what could that be.

The engine won't start, there is no spark. I receive the error code 54 and have no more ideas for it.
The starter is ok, it's cranking, but the engine will not engage.
The fuel pump relay seems to be working, as I can feel it "click" on when the key is turned to start the car. I also hear it working when I stand close to the tank. Fuel filter looks like it must have been replaced recently.
I have the power module and the turbo logic module as 2 separate parts (as in 86-87 models).

It happened few times that the engine started while cranking, then it worked for a while and turned off suddenly. I even got it once working for like an hour and then I had to tug it back home. So sometimes something happens and the spark shows up, but it happened only like 5 times.


Already tried:
Replaced pickup sensor under the distributor cap for a new one.
Replaced the ignition coil for a new one.
Checked fusible links: they are ok.
Checked all wires: they are ok.
Checked on the two small wires on the back of the alternator during engine cranking: one of them has full battery voltage.
Checked the map sensor: it is ok.
Removed the rubber from the inside of the power module, checked all of the connections: they are ok.
Replaced one of transistors in the power module for a new one.
Remove the distributor cap and watch if the rotor turns during cranking: it does turn

The computer might have been already replaced once because there is written: "81 dodge b4 600"


I think it could be the logic module, but before replacing it I want to be 100% sure that I checked every other possibility, because it is an expensive adventure.

I will appreciate every useful hint, hoping for finally getting it repaired.