This is one i'll never forget, the ign wires [MSD] new cap [VENTED] alum contacts, experiencing po300 code - no start intermittent, END RESULT, while replacing coil wire with copper core. while removing wire from coil a lot of white powder fell out, corroded dist. alum. terminal, moisture getting in through vented cap leaking up coil post on cap. At times causing no start. Found brass-copper term cap @ Rock Auto, about $8. , sealed vent with silicone.
I live in damp climate Fl. , even though stored in garage. The term. from inside of cap not totally sealed.
Still running copper coil leed to cap, coil within 13 in. of dist., 60 yrs. of turning wrenches i've never heard of this. Never too old to learn