TDi trucks suffer from water ingress as well-they have an ECU too
I removed each plug wire, cleaned around the cap and wire and then smeared silicone into each plug wire and insterted the plug wire into the cap.
On the coil, I again cleaned the connections and then smeared silicone not only on the wire to the coil, but also to the wires on the primary side.
Also, there are a few opening on the bottom of the distributor body-in the old days, this was to vent ionized air so it would become conductive, but without breaker points, I'm not sure why this is necessary without the points opening and closing-er, now that I think about it, there is this arcing when the rotor turns. Maybe we do need some venting.
Peace,
PT