Wierd Brake Noise 2001 Jimmy

My vehicle has just started to make a grinding sound whenever the brakes are applied. Seems to be coming from drivers side front. The pads are fairly new and still thick, at least 1/4"or more. I looked at the rotor and It looked like it had seen better days so I replaced it. No luck. Also looked closer at the pads while rotor was off, they look good.The noise makes it sounds like the pads are made out of rocks. Any help?

Pull wheel and spin by hand while someone pushes the brake pedel just a little.
Also Check for a rock in there or tin shield rub or other stuff rubbing.
Did yo greese the sliding pins good?

Did you use a good quality brake pad?
Any chance the brake low pad scraper is bent to where it is rubbing?