Toyota Repair: Brake Boost line Toyota Solara 1999, toyota solara, airplane engine

Question
Recently my '99 Solara started a high pitched and non-stop whine while I was driving. When I brake the whine gets louder. When I shut the car off the whine slowly dies--sounds like an airplane engine shutting down.  At one of these quickie oil change places the guys told me they thought it was my brake boost line making the noise.  If this is the problem, is it covered by warranty? How much would it cost typically to fix it?

Thanks

Answer
It sounds like ther may be a problem with the brake booster leaking vacuum inside the car,  this is very unusual and have never experienced this on a Solara, it's possible that the vacuum hose to the booster is making the noise, try replacing it first.