Any suggestions as to why when cold (below 15*f) at start up and first braking my pedal is super hard to push and truck does not want to stop. After the first stop or if I push-release and push again it softens up and acts normal. Only does it when really cold and at first braking.

 

Vacuum problem in the boost cylinder. The seal gets hard and leaks air. A booster works by developing a negative pressure, using vacuum from the engine, to assist. This makes the pedal feel softer so to speak. Simple solution is to pump the brakes a couple of times after you start before driving.

 

I could also be that your brakes are freezing over night. I know mine have been freezing up lately and so I just have to remember to test the brakes before getting on the road.