So everytime it rains.. after about driving in rain for 20 mins..when I go to hit brakes car idles high. About 3k or so...even when I come to a stop..so I went through every vaccum hose. Brake booster line and all of it..so I did some research on here and some guys are saying stoplight switch under dash.. which is werid..so I disconnected the stop light switch under dash and bam..no high idle..what the hell..conect it back car goes back to high idle...now if I wait over night and next morning go to start evo and then car Doesn't to it again till next rain storm....help ppp meee

 

So to summarize: When your car is driven in wet conditions, the idle will hit 3k while stationary while pressing on the brake? Disconnecting the switch on the brake pedal that activates your brake lights solves the problem?

 

That is correct..no vaccum leaks. Or anything like that. Werid. Need help anyone experience this before

 

It sounds like an electrical gremlin, i would start by inspecting all the wiring harnesses going from the fuse panel back to the tail light housings. Also check all grounding points and make sure they are nice and tight. If everything looks good you will need to bust out a multimeter to start troubleshooting different parts of the circuit.

 

It could be that your brake booster is leaking when you apply the brakes. Although it doesn't explain the rain part.

Drive the car around until its warm enough that the issue starts happening then Unhook the master cyliner and block off the intake manifold end and see if the issue persists. I would advise against driving without the booster hooked up, maybe just try it in a parking lot.

Another idea: Do you have a wide band? If you see it go briefly lean when you step on the brakes that could be a sign of a booster leak.

 

This is almost 100% a vacuum leak somewhere. Brake booster, valve cover, etc. Start with a spray bottle and then go to canned smoke if you are unable to find it audibly or with the soapy water.

 

I had the same problem, it was the wire connectors on the drivers side.
Scary situation when you brake in gear and the car revs.

 

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