I need some help ! I just replaced the vacuum pump and power steering pump on my truck. Steering is working fine. Brakes work but I have no power assist. Cracked a line on the brake manifold to see if I was getting plenty of power steering fluid///yep got plenty of flow. Mash the brake peddle and it will stop but very slowly. Peddle is good with no leak down.

 

Try jacking the front end off the ground and with the engine running, turn the wheel full lock to lock and few times to get any air out.

 

It was the brake booster. I guess all that new pressure on a 285000 mile booster just blew the o rings out of it. Put a new one on it and everything is working fine.