Ford Ranger front disc brakes

I won a 1999 Ford Ranger XLT, 4WD, 4.0L, quad cab truck with about 96000 miles on it. The front brake pads were getting thin so I decided to do a brake job on it. I had the rotors turned, bought rebuilt calipers and bought new brake pads from Carquest. Everything on the truck is now back together but the brake pedal can be pushed all the way to the floor now. There is a little pressure on the pedal but it is not as it should be and virtually none when the engine is running. Everything worked fine before I replaced the parts. I bled the brakes starting at the passenger side rear, than the driver side rear to the passenger front then on to the driver side front. I still can not get any pressure built up. The master cylinder does not leak and I made sure that I checked the fluid level as I was bleeding the brakes. My fluid was not the cleanest when I started bleeding them but it now is very clean. Is it possible that there is something wrong with the rebuilt calipers? Could there be some dirt, etc. Stuck in the calipers from the dirty fluid? Or could it be something to do with the ABS system. I am stumped as I have done lots of disk brake jobs and have never run across this before. Please help!