2010 GMC CREW CAB BRAKE ISSUE

[2010CREWCAB]

I have a 2010 Gmc Crew Cab, the brakes are starting to piss me off, the CHECK BRAKES SOON LIGHT comes on all the time, I had the Dealer scan it and the Code Said Vaccum Issue, Soooo, ive checked everything up and down and cannot find this issue,so when you turn traction control and stability control off, and press the brake lightly and gas the pedel gets hard and the truck lunges forward, basically it will not do a brake stand, and i didnt try this to be an idiot. the reason i am looking into this is A, the light that annoys me and B, I almost got into an accident because I was driving down the road and when i pressed the brake the pedel went hard and truck didnt want to stop, and this happens occasionally I have noticed if I am driving and the RPMS are higher and i press the brake the pedel gets hard WTF!!! my guess is there is too much Vaccum but What do I KNOW does anybody have a simular answer or fix?