PS pump dying?

(Not sure this is the right forum- if not, please relocate).
2X within the past 4 months I've noted that starting the truck cold and allowing a couple minutes of warm-up had left me with no PS and no brakes. Brake pedal was rock hard and steering very stiff. After another minute or so, my steering and brakes had the power assist restored. Is there a check valve or failing vanes internal to the PS pump that would prevent the power assist on the brakes/steering? My guess is that after ~365K miles, something is bound to fail. PS fluid is at proper fill height and does not leak.

About your brake it could be a faulty hydrovac that could be the culprit. Yes you may be right the pump may be the reason of having a heavy steering wheel due to lack of pumping power through out the system.