PBR materials are heavily dependent on the textures created for them. 

Can you post a screen cap of the PBR textures you are trying to use, including the metal and rough maps that you say don't work right?  Not the full resolution because they are probably copyrighted, but perhaps a small screen cap (say 250x250 thumbs or whatever). 

With the proper maps, all you should have to do is connect them to the corresponding inputs on the Physical Surface node, or the Cycles root node with Principled BSDF texture.