Mercury mystique weird brake problem

Ok 98 mystique, v6, no ABS. Been driven in virginia, handed down to me by a family member eight months ago. I live in PA. It Has new pads, shoes and had new rotors installed 10k miles ago. car has sat for six months, I finally got it inspected and now here is the good part. When applying normal brake pressure the car acts fine stops fine, however if I have to go over that, it feels like the brakes do not want to grab very much at all, if I simulate a hard brake the wheels wont even screetch. I checked the booster, and diaphram, all check out good, replaced master cylinder and still the same problem. I should be able to stand on these brakes and they should lock, nope they are not even close to doing so. so Im lost, I bled all brakes and all air is removed and still, no go. someone please help me as to what may be the problem. I know my rotors are pitted pretty good, could that be the issue.

thank you