Brake issues

[Diesel Kinevel]

My situation: Every once in a while while Im driving or sitting in traffic, my brake pedal will harden up like Im losing power breaks. the parking break light will flash off an on occasionally during this "episode". Do you guys think Ive got a air bubble in one of the lines or is it maybe my booster taking a dump? any help would be greatly appreciated!

 

[action4478]

More likely its the vacuum pump.....

 

[Crumm]

I would also say Vacuum pump.

 

[Diesel Kinevel]

Is there any way to know for sure if its the vaccum or not? also what would be the price give or take on one? thanks!