[Marotte]

I ended up bringing the car to a knowledgeable mechanic, that also diagnosed an ignition problem. The MSD primary ignition seemed to be the culprit.

But after some talks directly the MSD tech people, it seemed a possible issue was in the wiring: the power in and out of the box were running parallel, and it may cause interferences.

I'm kind of skeptical, since it was running fine before, but not wanting to buy another primary ignition if not necessary, we rewired it.

Time will tell if it really was the issue...