Strange sound

The car was fine all day until I started it about 3:30 and all the sudden its making a noise like air escaping...took it back to the house and started it up again and it was worse now it sounds like a teakettle whistle every time the car runs but the noise stops when ever im pushing on the gas pedal (not just revving it)...i dunno what it is and since i dont know what it is i can't fix it...The car is a 67 Mustang

This is a classic intake manifold vacuum leak.

Chances are it's one of the vacuum lines has come loose or is leaking, either at a fitting or it's developed a split or hole somewhere. The fix is easy, just run the engine at idle, lift the hood and follow the noise to the source.
It's possible the base gasket of the carburetor is leaking, too.

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