Q: changed calipers, brakes and my 06 GMC still sticks and ssmells smokey.

Ok the breaks on my truck out of the blue started getting hard while i drove and if i released the gas it wouldnt glide or if i pushed the breaks once i released the brake it stands still. then there was this awfull smell like burning. So i had my two front brakes and calipers replased. the front passenger caliper and break was definetly burnt when i removed them. The breaks were blead and only for a day the truck drove good then same thing happens. So then the brake fluuid was checked and it was dark and seem to look like there was water in the sysytem. So then the whole line was emptyed and refilled. My truck then drove good for 2-3 days and now im back with the ssame problem. any solutions or pin point the problem. please help.

Thank You Guadalupe Sanchez
My car has an automatic transmission.