Vacuum fluctuates when brakes applied

dano said
Does the idle go up or down for begin to wander when you hit the pedal?

Idle gets affected when brakes are applied and

dano said
Does the idle go up or down for begin to wander when you hit the pedal?

Yeah, idle goes down as with vacuum (2-5”) when I apply brakes, when I release brakes idle drops 8-10” then slowly comes back to 10-20” of vacuum and idle gets restored when vacuum goes back to normal.