2001 Brakes: Master Cyl or Booster Tank?

[userissue]

Hi,
I have a 2001 V6 Solara. I think the brakes are spongey, other people say they feel fine. They stop, but just don't feel right to me.

One thing that I have noticed is when the car is not running, the brake pedal goes down about 3 inches and feels firm. When I start the car, it pretty much goes to the floor.

What do you think it is? My best guess is the booster tank or the in-line valve going to the tank.

Thanks,
Randy

[Stealthee]

The pedal will be hard to push when the car is off because there is no vacuum assist. If the brakes feel spongy the firstvthing I'd do is a brake flush.