Power loss Vacuum leak?

Good Morning - I have recently purchased another Vette. 1979 L48 Full Option.
Everything works on the car - Lucky for me! However, I have only one issue.

Here is the question...

If if try to take off, Full Throttle - a sound comes from the engine and I lose power. It quickly regains and off she goes. (sounds like air blowing off)

If I try to do a break stance, the same sound comes from the engine and as long as i hold the brake pedal down, I have no power, I let go - full power is restored and off she goes.

I found that the vacuum line to the brake booster came off once - I put it back on, put a clamp on it and that was fixed - however - the power loss on an aggressive take off or brake stance remains.

Where would a vacuum line or blow off valve be under the hood that would cause such a power loss and immediate power gain after I let the brakes off?

You help is appreciated!
Best Regards
Darren