Exceedingly high RPM

So here's the story:

My sister thought she could run her 97 SE 3.1L through 3 ft of water and not worry about a thing.Of course the engine takes a drink and dies. Miraculously its not damaged (just needed a good drying, mechanic said)...until now?

Her brakes don't work too well. No matter the gear it revs high..almost redlining a few times. Mechanic says he's got no idea other than its a sensor. Which one he doesn't know.

I'm thinking TPS or something with the ignition module. Maybe even the PCM.

Any input from you guys?

Is the engine reving while in park or when stepping on the gas? If it is in park I would look at the PCM as sending wrong signals although you should see some trouble codes, like having the check engine light on. If not then it may be a problem with water in the transmission causing it to slip. Drain and replace the fluid and it should be fine if the latter is the problem.
If it were the ignition module you wouldn't get it to run as it would short out and not start. The TPS could cause this by the computer not sensing when the car is at idle or full throttle.
As for the brakes. There shouldn't be anything wrong except for the brakes needing to dry out. If she has drum brakes jack up the car and remove the wheels and the drums. Allow them to cook in the sun and then adjust them and they should work fine. If the front brakes don't work well then you may need to change pads but I doubt it due to the fact that they will dry easily due to heat generated when braking and the material doesn't usually draw or retain moisture. Hope this helps.

According to her, the mechanic said nothing was coming up on 'the machine' which I assume is some kinda ODB reader or somesort. Only doing it in park/neutral, she says its fine in gear. The mechanic is going hose by hose, wire by wire for us.

Water just wasn't made to go in an engine :p