Hi,

You have said that the engine is newer as in less mileage and so forth.
I think I understand that the engine you are trying to get running is not original to the car.

So, it fell from the heavens into your hands and it’s just magically better?
I would think not.
Did you go through the timing belt replacement procedure while it was easily obtainable out of the car?
Roll the engine around by hand to number one hits on the crankshaft mark and peel back or remove the top cover to see if the camshaft dot.
It is supposed to be at the top of the curve or aligned to a line on back cover plate.

Just because it turns dies not insure that it will stay in time or was even in time for very long if it was slack in the beginning.
You said it had a “raspy” sound.
I think the RASPY might be a clue.

I would not discount the CPS in its entirety either as they do fail in mysterious ways as so does the ignition coil relay behind the battery.
Those two items are the timing in a nut shell.
The 1990 was only the second year for the new system of electronics that turned out very nicely after a few modifications and one was the CPS. The next one was adding and pre start running of the fuel pumps.
Your may or may not have that. It was an ECU internal change.

If you think the timing belt is up to snuff you will have to flood the intake manifold with starting fluid vapors
to rule out a total shut down of the injector side of things.

You spray the fluid into the nipple connection where the Fuel Pressure Regulator vacuum line goes.
The FPR is another vote of contingency as if it fails open all the fuel gets returned to the fuel tank.

Using Starting Fluid bends the arrow of troubleshooting directions a bit.
It’s a good technique to use on any size combustion engine.

Give it a shot! 😵‍💫

Phil