Firing problem

Are the spark plug wires good? What makes you think you do not have good spark? You can use a digital multi-meter, low voltage setting, very lo tech, not invasive. Engine idling, touch meter lead to spark plug wire, do not penetrate the insulation and do not take plug wire loose, it is an inductive reading. Some of the readings I have seen are around.6 or.7 volts. The point is, if you get a reading that is bouncing off zero, that is where you start testing. The spark plug wire will lead to the coil, you could swap coils to different positions to see if problem follows the coil. As far as the ignition module, you can remove the single coil. Use test light on primary terminals at ignition module, engine cranking, the light should flash. Disable fuel injector/s.
Make sure battery has a full charge and connections good. Make sure ignition module has good voltage and ground.

Yes, possible. How long since a tune-up? Any applicable trouble codes? Your obd1, you should be able to check some codes, yourself. I hate to see you throw parts at it.