1999 K3500 brake problem

I have hydro boost brakes and they are acting like something is wrong with either the power steering pump or the booster. It whines sometimes when I step on the pedal like I am low on fluid, but do not feel it in the steering and the pedal gets so hard to push it doesn't want to stop sometimes. It has had almost everything on the brake system replaced. I almost went through a store front today pulling into a parking spot. any suggestions? I would appriciate any input if anyone else has had this problem. Thanx

Need to have the power steering pressure checked, its possible the pump is worn. If the pressure is ok, then the problem is most likely in the hydraboost unit.

Need to have the power steering pressure checked, its possible the pump is worn. If the pressure is ok, then the problem is most likely in the hydraboost unit.

I don't know how to, do I need to take it to a shop? or can I do it at home?

Pressure test would need to be done at a shop. Not that hard, but special tools are needed. Pressure and flow can be measure with a power steering analyzer(thats the tool needed).

It's been a while, but I changed the power steering pump it helped a for a but the problem is back. The (ABS) light comes on now and stays on longer. I'm wondering if it could be a wheel speed sensor?

Wondering about things is good. However this doesn't work well with the newer cars. The thing that does work well is a good diagnostic scan tool in the hands of a good mechanic. One thing you can try is pull the ABS fuse and see what happens. This will put the ABS lite on constantly, and will inhibit all ABS functions. But if it cures your brake issues, then you don't have to wonder anymore.