1992 Chevy Truck problem with brakes

There was a problem with the brakes the parts are all new pads rotors drums lines. the pedal was falling through and there was a swoosh sound when pressed. we replaced the master cylinder and the praportaning valve, ive bleed the brakes everywhere possible multiple times and the pedal still goes all the way down with the same sound. the only thing left is the booster but thats not fitting the symptoms. please help