99 Intrepid brake/brake pedal problems Please help

I have a 99 intrepid with 2.7. This winter I started having problems with the brake pedal freezing up and when it would finally work air would come out from the pedal. It still does the air releases when I go out on the highway and up a hill. The brake also starts to get stiff after a few stops until I lift up on the pedal the it releases. I have recently to this car into the shop. And told me that the calipers are ceased and I all new brakes. But I have also talk to a few mechanics and the say it is probably power booster and vacum lines. Which could it be? And does the power booster affect the calipers in a way to make them appear to be ceased beacause of lack of presure?