Really heavy rain then want rev over 3K for a short while

Happened this week that the car was out parked for a while with driving rain coming into the engine compartment. Started fine but initially didnt want to rev cleanly above 3K or so, was OK after a little while (i presume it dried out). Whats likely to be getting wet and any suggested mods/cures?
Cheers

Anyone have rain related issues please?!

I’ve not and mine lived on the drive for 3 years, even came home to find it had a foot of snow on it once!

I made a shaped cover for the engine compartment for when away from my garage, and if I think it’s going to tip it down.
It’s just a waterproof material with 4 rubber ‘studs’ that push through the grill

Sounds like a plan, do you uave a photo please?