Dragging or Grabbing Brakes on 1997 Chrysler Town & Country Van

I recently relplaced nearly the entire brake system on my 1997 T&C van. I've put new front calipers, pads, hoses, master cylinder & machined rotors, but still have a front end brake noise. When driving at low speeds everything is fine, however when I get to about 15 to 20 MPH front calipers begin to grab & make rubbing noise.

I've checked power brake booster, vacuum hoses, pedal mechanism, bleeding of lines, etc with no faults found. Proportioning valves appear to be working since I don't get rear wheel skidding upon hard braking.

I've been unable to diagnosis the problem so I jacked the front end up & removed both front wheels. I had a helper release the brakes & slowly accelerate. The rotors operate smoothly for a while then at about 15 MPH they beging to grab & make the noise I hear when driving. I understand that when released, the brake pad to rotor clearance should be about .012 of an inch. I don't have this much clearance, but rotors do rotate freely at lower speeds or when turned by hand.

Caliper guide pin bushings have been greased properly & pad wear is uniform. The ABS system appears to be working properly ( I assume this since the ABS warning light is not on). Entire system was bled properly & brake fluid does not appear to be contaminated.

For some reason as speed increases to about 15 MPH weather on the road or jacked up, the front brakes begin to grab or drag. Any suggestions on possible problem????

Optional Information:
1997 Chrysler Town & Country 3.3L

Already Tried:
Replaced all major compnents