Pontiac Repair: Rise in RPM, most newer cars, pontiac grandam

Question
My mother-in-laws car is a 1997 Pontiac GrandAm GT with about 105000. Her car has just started reving to 3000 RPM whenever the brakes are applied. She brought it to the dealer but they had no idea what could be causing it and have never heard of that problem before. Do you have any suggestions as to what could be causing it to do that?

Answer
Annette,
I too have not herd of this but since most newer cars have power brakes and the engine plays a part in the operation I would look there. If the power brake diaphragm is skewed it may cause a vacuum leak which would or could cause the engine to get extra air and raise the engine RPM. I would disconnect the brake light switch under the dash if it's found not to be a faulty power brake problem. If that's the case and it lowers the rpm I would get back to me or replace the engine computer. The easiest way to check the brake part is to crimp off the vacuum line to the power brake system. If when this is done the two are separate and thus won't effect each-other. If the problem stops I would replace the power brake vacuum assist.
   Now things happen when you hit the brakes, one is the engine twists a bit and it there is a wiring problem it could cause something to become ajar or a circuit to ground or become open when it shouldn't be, thus causing the engine computer to spin out and all kinds of things can happen. I have found there is a ground wire in the area where the engine and transmission connect on the front side of the engine way down if your looking from the top over the radiator. This ground will skew and cause things to happen from a stalling to not running to ??? so I would check this as well. Hope things go well.   
            John