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.

 

Common problem is the vacuum check valve.. .Replace the vacuum check valve on the brake booster. It's a one way valve that gets stuck and doesn't allow vacuum into the booster. I've had two toyotas that did this.

 

I would also make sure the fluid is flushed out and new fluid added. I seen fluid that is probably the original fluid from the factory.