Brake Pedal Pushes Hard
 

Hi. I have a 2000 Saab 93 with 196,000 miles on it. Recently, the brake pedal has gotten very difficult to press. The initial part of the pedal travel is pretty normal, but when I press farther, as I'm getting closer to actually stopping, it's like there are no power brakes at all. I can also hear what seems to be air bleeding out from under the dash as I press the pedal. I suspect the brake booster, but that was replaced only 2 years ago (40,000 miles) with a new booster (part alone cost $358). They also put in a used master cylinder at the same time. The symptom then was that the brake pedal would depress, but wouldn't return, so I had to pull it back with my foot. This time, the pedal just presses hard.

Any ideas on if there could be another cause?

Thanks for the help.