GMC Repair: Brakes, rubber brake hose, gmc safari

Question
HELP! I just bought a 1992 GMC Safari Minivan W/AWD and 4WABs. When I drove it I first noticed a hard pull to the right during moderate to heavy braking. So I set about replacing the linings, pins, guides. I found when I tried to use a clamp to retract the LF caliper that the piston would not retract, even with great force. The RF worked fine. So I replaced the Caliper. Bled it and test drove it. It still pulled to the right under breaking. and now I noticed a drag and overheating on the LF tire. I removed the caliper and had the wife press the break pedal while I watched the piston it moved very little. I then tried to retract the piston to reinstall the caliper and It too would not retract, Keeping in mind that it was a new caliper. I loosened the brake line to the master cyl and tried to retract the piston to no avail. I feel as though the ABS pump, valvebody, modulator ASSY is the cause of the problem. Please advise!
-Carl

Answer
Hi
I would first check the rubber brake hose from the steel line to the caliper.
The rubber hoses have a LONG history of blocking up.
If it checks out OK, keep finding other brake line connections where you can seperate the lines and check for fluid flow.
Try blowing out the line from the EBCM to the caliper.
USUALLY, the EBCM will not make a locked up condition, but rather no restriction at all, making a VERY spongy, low pedal.
I Hope this helps
JUST ADVICE from experience.
Good Luck
Pawl