My car recently has had problems.
When I start it, it sometimes (not always), idles very shitty up and down from 500 to 2000 rpm. Then when I drive it jerks. The thing is it only happens if it is raining, and sometimes after I get a car wash. I'm not driving through any puddles. Its just minimal water causing this.
I'm too scared to drive it now because I have a feeling water is getting in the intake.
Am I right to assume this? How serious of an issue could this be? Whats the best way to permanently prevent or fix this?

 

The idleing up and down is normaly caused by a dirty throttle body.
Check your throttle body (before the supercharger) and see about
cleaning it. There are forums arround here about how to do it. The
jerking might be the same thing. Dont know about the water though....
If you can manualy rotate the engine by hand in the direction of rotation,
give it a shot. General rule of thumb is 1 blade per cylinder. (This is an
old Radial engine thing for aircraft to makeing sure oil hasn't filled/locked up the lower
cylinders) However if you get water in your engine, the concept is the same.
So if you turn your engine by hand through about 4 revolutions, you should
have the water cleared out. If the engine gets stuck. Then you got water
in the cylinder thats on compression. The water isn't compressing, and
the engine WOULD have been damaged had you attempted a start.