[ImperialCrown]

Electrical components, more than fuel components are affected by moisture. Particularly high-voltage components like cap, rotor and wires.
I have a water spray pump bottle that I use for misting suspect components. You may see arcing or get misfire while testing the area.
There should be a black plastic water shield over the distributor cap.

 

[dana44]

Absolutely agree. Between distributor cap and sparkplug wires, dampness you mention can allow the electricity to pass the shortest distance through it and make her run rough, then quits when the engine warms up (and evaporates the dampness/moisture), and she runs fine. It is time for a new set of sparkplug wires, distributor cap and rotor.

 

[B10alia]

+1 on dana's suggestion. As the gap between the ignition rotor and wires widens, the voltage required to fire the plug goes up. If there's moisture providing even a high-resistance path to ground, it may still be less than the now-increased resistance between the tip and terminal.
If the engine is running like (bear with me on this, this is really the best way to describe it) harrumph-harrumph-harrumph, it's probably misfiring on one cylinder, pointing to the distributor and everything downstream. If it's rough and struggling, but evenly so (doesn't struggle cyclically), it's probably upstream of the distributor. Either way, rotors and wires go fast in these cars and should probably be replaced.

 

[ImperialCrown]

Quote: "harrumph-harrumph-harrumph".

I like that. Could I use it? :lol:

 

[B10alia]

Absolutely, IC! And if you've ever run a K engine without one of the spark plug wires connected, you know exactly what I'm talking about...