I double checked and my foot isn't hitting two pedals at the same time.

Say I am driving 30mph and step hard on brakes...I would slow down and hear engine idle go up. I have no foot on gas, so I should only hear the idle rpm.
When I am not moving and step on brake, nothing happens (idle stays the same)

Makes me wonder if perhaps the fuel is being rushed in while breaking hard??

Got carburetor and engine mounted mechanical pump.