Noticed that my 305 TPI was running and idling a little rough lately. Took timing light and determined that cyinders 2 and 5 are sparking sperratically, all of the other ones seem to be fine.
New MSD wires - only 10K miles on them. All check out for resistance.
Replaced with MSD distributor cap (by the way 3X as much, but looks identical to a cheap China one I put on last year). - No difference.
New MSD Coil 10k miles ago.
Spark plugs less than 10K
Noticed in the old cap, some of the brass termnals appear to be burnt, or to have some trailing spatter of some sort. Not sure if you can see from the images.

Any thoughts? First thought was ignition control module?

 

Any thoughs? Do the terminals in the distributor cap look strange the burning on the terminals?

 

First, get rid of all of that MSD junk and put some OEM or OEM replacement parts in there.

Second, you say 2 and 5 are intermittent. If that's true and accurate, how in the world could it be the ICM?? The ICM is not specific, in any way, to cyl's 2 and 5. It says, "Ground-ground-ground-ground-ground-ground-ground...." to the coil, so it can in no way, discriminate specific cylinders.

What is specific, to cyl's 2 and 5, in the ignition system: Cap, wires, plugs. Look at those.

 

Thank you for your thoughts. Unaware of how the ICM worked, and thought MSD was quality. Genuine coil ordered. Ill work on the other diagnostics.