Q: Bad Brakes on 1994 Ford F-350

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I have a 94 F-350 4x4 crewcab. The brakes make a rushing sound, go near to the floor but still stop the truck. It almost feels like the back brakes are doing nothing. I know the rotors could use being turned. The man at the garage said i needed a new power booster master cylinder after i had new shoes put in the back. Problem is i dont trust him, he didnt bother to bleed the brakes after he worked on it the first time. Is he right? Ther truck stops but i get the brake lights and i have to pump it.
(1) Answer
The most likely cause of the "rushing noise" is a failed vacuum brake booster. Start the engine and put your head under the dash while applying the brake with your hand. A vacuum type sound may indicate booster failure, but not the long brake pedal travel. If the rear brakes are drum style, make sure that they are adjusted properly- this could cause a soft brake pedal. If the brake system is bled properly and there is no system leaks, a master cylinder or a "RABS valve" (rear anti-lock brake solenoid) may be needed.