My brakes were sticking so I changed both calipers,rotors and pads.semmed OK them started doing it again.I bought an new mastercylinder but my chilton book says I can't do it because it connects straight to th ABS modulator .is there anyway I can do it.it's just a work car and don't want to take it to the dealer and pay big money.

Did you lubricate the caliper pins with silicone grease? This simple (frequently overlooked) step might solve your problem.

It could also be that the brake hoses are partially collapsed internally.

There's probably no way to check the lines is there?I know when I bled out the new calipers the fluid squirted out with good pressure.

What led you to believe it was both calipers? Are the rims getting hot when you drive or are you going through brake pads?

If the brakes are sticking (not releasing after they are applied) try opening the bleeder screw while that happens and see if they release. If they do, replace the hydraulic hoses and re-bleed the system. Road test again and hopefully the problem will be resolved.
I hope this helps.