Front breaks not releaseing at times

For some reason my front breaks will stick causeing major strain on the motor as well as burning up my front breaks. It dose it at random usely after i drive it for a bit. First i changed the passanger side calipluar with a brand new one $60 bucks and it still sticks. Then i bought a good used mstr cly at the parts yard and installed it and it still dose it :headbang: I was thinking it might be the booster but then again if that was the case both front and back would do it so that rules that out. Only thing is left if theres a problem in the front break lines. If i cant figer it out im going to buy a set of front lines at the parts yard and change them all out on the fronts. is this hard to do?

Any one have any ideas what else it might be causeing this problem?