Toyota Repair: 1998 TOYOTA CAMRY BRAKES, caliper piston, toyota camry

Question
MY BRAKE PEDAL GOES DOWN ABOUT AN INCH FROM THE FLOOR! I HAVE ADJUSTED THE REAR BRAKES,AND BLEED THE SYSTEM. SINCE THAT DIDN'T WORK, I PUT ON 2 DIFFERENT REBUILT MASTER CYLINDERS THAT I BOUGHT,I BENCH BLEED THE MC BEFORE I PUT IT ON AND BLEED THE SYSTEM AND ADJUSTED THE BRAKES  EACH TIME BUT THE PEDAL STILL DOESN'T COME UP. I CHECKED THE ROD LENGHT IN THE BOOSTER AND IT SEEMS OK. I DON'T KNOW WHAT TO DO NOW, HOPE YOU CAN HELP?  THE 98 CAMRY IS A 4 CYLINDER. MY BOOK
SAYS FOR BLEEDING RR,LF,LR,RF IS THIS CORRECT?
I HOPE YOU CAN HELP! I'AM STOMPED!! THANKS JIM

Answer
If you are absolutely sure there are no leaks do the following:
Remove the front wheels
Remove the caliper piston housing
Remove the brake pads
Check the sliding pins on the calipers that allow the caliper to move on the caliper bracket as the pads wear down
A common problem is that the pins get rusted inside and the caliper cannot move and the result is a low brake pedal
If this is the case, free up the sliding pins with penetrating oil and lube them with an antiseize compound and put everything back together, let me know if this fixes the problem.