I have a 95 nissan pathfinder v6 and i'm having this problem on it whenever it rains, it runs very poorly unless full throttle or higher in the rpm range. Sometimes can take a couple days to clear up once the rain stops. Any ideas???

Its had a tune up fairly recently including cap and rotor, and there is no moisture build up under there. Nothin in the engine bay really looks wet in the rain. I'm thinking it has to be an electrical problem because it only occurs under these conditions not all the time. The check engine line intermittently pops up sometimes too, but i dont know how to pull the code....