Power brake issues in oldsmobile?

im having trouble with the brakes on an olds alero. the pedal is hard to push and the engine teprature climbs marginally when you brake. This leads me to believe that there is an issue with the vacume line for the booster. am i right? are the power brakes powed by vacume in a car this new? (later than 2000) if so how do i go about fixing the problem?