Thunderbolt Ignition problem

[MSteinmann]

Looking for some help, I have a 1986 mercruiser v8 (350 Chev) that has the thunderbolt. I noticed the engine was idling a little rough. A short time later the engine stopped ( like you turned the key off). I changed coils from the other engine and it started back up however still rough. I bought a new coil and installed. Went back to go out, started the problem engine, it ran about 1 minute then shut off. I have power to both posts on the new coil. Engine spins but won't fire. I took the wire ( cap to dist. ) off and no spark from the wire. I am reading about the knock sensor and ICM, I have seen that those parts are unavailable? Should I replace the ICM and sensor, or try to find a replacement distributor and eliminate the ICM?​
Thank you!