Any chance the module is not getting a good ground? How about heat sink? It must sit nice and flat on a surface to dissipate heat
I would increase wire size to the module (you said 18?) but frankly doubt that is this problem
There is only one correct polarity for the pickup wires. It's called "rotor phasing" Google that. If the dist. has been apart, or something slipped etc the phasing can be off. This refers to the point in rotation at which the spark is triggered vs where the rotor is pointing in relation to the cap contacts. If this is off, the spark triggered between cap contacts, it will run poorly. Crossfiring, etc. A timing light alone will not show this up
At this point I would "just try" another coil ANY coil. I actually used a factory Mopar coil on my conversion.
Other than what's been covered above, no new ideas. If you have a spare dist. I'd try it too
