I have recently started having an issue with my brakes when I first crank the car. I have a '98 4.6 with 115k miles. When I first crank the car I have no brakes for the first 30 seconds or so. It isn't a big deal unless I am in a hurry and don't wait for the brakes to "build". Once the brakes start working, I have no other issues with them. Also, they don't have problems after quick start and stops. The only problems come when the car has sat for several hours. The brake pedal feels fine, but there is no stopping the car. Any suggestions?