Yesterday the front brakes locked up. I was driving and it was acting wierd then i realized that the brakes were engaging so at first i thought it might be my parking brake partly engaged, but it wasnt and it just got worse fast. I was thinking it was just one caliper, but it was both front brakes. Does anyone have any idea where I should start? I was thinking maybe the proportioning valve. Any help would be great.

Water. Try this first remove the wheels and wash the rotors and calipers clean all the mud out of them. Then check the pads is there enough pad left. My rear disc's were locking up on me come to find out they were clogged with mud and wouldn't release.

dude dont even waste time cleaning or"fixing" just go buy 2 new calipers
had the same thing happen on my yj went down to auto zone bought som lifetime warrenty calipers and pads for like 100 bucks and if it happens again they will replace the caliper free:

not trying to plug az but sometimes a warrenty means alot

Well of course it was the last thing that i ever would have thought. I checked my brake pads and all were fine. checked the master cylinder and it was leaking so I changed it. Still locking up so i pulled the vacum from the booster and there you go the brakes came free. It was my booster. havent changed it yet but will shortly. Thanks for the help yall.