Brake pedal moves when revving the car

[bnight]

Ok so I finally installed the Power Pack 3 to the GT and when parked I decided to Rev the engine to like 4000 rpm or so what was strange was that when I apply the throttle the brake pedal was moving up when I stopped the brake pedal moved down. I did full service of the car including brake fluid at my local dealer who also installed the Power Pack 3. Brakes feel great though but for the past year or so I'm chasing a random hard pedal on track. I was thinking brake pads but now I start to think brake booster check valve. Any inside will be helpful.

 

[TMSBOSS]

Check valve, Check.
The manifold vacuum will usually vary with RPM and throttle position. The check valve should hold vacuum steady.
Check the valve and if you can, pull a vacuum on the booster and see if it leaks down.

 

[bnight]

Check valve, Check.
The manifold vacuum will usually vary with RPM and throttle position. The check valve should hold vacuum steady.
Check the valve and if you can, pull a vacuum on the booster and see if it leaks down.

Yeah I lean towers check valve as well will probably just order a new one the brake booster should be fine if the pedal is going down when engine start. Though my pedal do get hard after a few days when car is sitting.