95 astro brake problem

Hello everyone: I have a terrible brake problem with my 95 Astro AWD hydroboost system . All my brakes lock up , all four wheels, but they do release in five seconds . The pedal feels horrible, hard as a rock but braking feels soft and mushy before they lock up. I have bled the system, but it didn't help. I have new rotors , pads, brake shoes , drums , hardware and still nothing helps. Any help would be appreciated.

Does the power steering operate smoothly when you turn the steering wheel from full left turn to full right turn? Is the reservoir full of the correct fluid? Is the serpentine belt tight? If not, the belt tensioner may be worn out or broken. Are there any abnormal noises from the power steering pump? Does the vehicle have ABS brakes? Is the brake master cylinder full of DOT3 brake fluid? Those are the basics with that system. Check them and post your results back.

Does the power steering operate smoothly when you turn the steering wheel from full left turn to full right turn? Is the reservoir full of the correct fluid? Is the serpentine belt tight? If not, the belt tensioner may be worn out or broken. Are there any abnormal noises from the power steering pump? Does the vehicle have ABS brakes? Is the brake master cylinder full of DOT3 brake fluid? Those are the basics with that system. Check them and post your results back.

I have checked everything you mentioned, and there all fine. It does have ABS brakes. I've never experienced anything like this before . I've worked on cars all my life and I've never run across anything like this. All the brakes bleed well and the fluid is clean because I've dumped so much in it to make sure there is no air in the lines. I know this is a rather rare experience, but I'm sure that someone has experienced the same problem. Thanks for your reply

Have you changed wheel/tire size from stock?

I finally have a victory over my brake problem. All three hoses were detective. First changed the one in the back and it straightened out the back brakes and changed the passenger side of the front and that wheel straighten out then went over to the driver's side front and changed that one , now everything is fine, just like it should be. What a nightmare!!. Thanks everybody for their input. I'm sure most of you were puzzled like I was