Another brake squealing problem!!

[CapSS92]

Hi Tobin, thank you VERY much for your reply. I am using C5 calipers and pads from Autozone. They sell them assembled with abutments and all clips. All I had to do was mount them onto the bracket. I made sure that the rotor was centered and that the caliper had equal spacing on both sides. As for the rotors I am using Raybestos C5 rotors cross drilled and slotted. The noise is coming from the rear. I added some washers between the MC and hydro and the noise seemed to stop happening while driving with no brakes applied. I cleaned off all the rear today and took it out for another drive. No more noise while driving but it happened while braking after about 10 miles of driving on the freeway and only while applying light pressure as I was either coming to a stop or just pressing them as I was going about 10 miles an hour. If I stepped on them hard, there was no noise. And the rear wheels had a light coating of dust again. It doesn't seem to happen when I first use the car or if it's been sitting for an hour or so. As for the setup, I consider it newly installed as I just finished the car and it's only got about 100 miles of driving on it, spaced out over the course of a year. When I first started driving it to shake out all the bugs there were no issues. I hadn't run the car in about 3 months and just started driving it again at the beginning of this month when the noise started.
I had also adjusted the MC prop so there was little or no pressure to the rear and I still had the noise when braking. I'm beginning to wonder if it's not the pads or a stuck caliper. Any way to check?
Again thanks again for your help Tobin. I'm just extremely frustrated with this.