Rough Idle in the Rain
 

hey guys,
Ok so awhile ago i noticed i had a rough idle. Ok so i did the usual, checked my plugs, ran some injector cleaner, increased my idle speed by about 200 rpm. Now heres the thing, she idles perfectly in normal conditions. The minute it starts to rain the idle drops from the usual 900 i have it set for (yes i know thats a bit high) to about 550-600 and is pretty rough. Its not stall out rough but its still annoying. Is there anyway to fix that ? Does anyone else have this issue ? Thanks guys.

Sounds like a water going into the AIR FILTER ???