i know its not a mustang but the left front caliper on my 1988 bronco seems to be sticking when i hit the brakes, or it just seems to grab harder than the right side

i rebuilt everything using new rotors bearings calipers brake pads and the soft brake lines on both front wheels not to long ago and i figured that would solve the problem but it didnt. What could be causing this? is there a proportioning valve somewhere that could be bad?

also, yesterday i got in some mud and now the left front is squeaking, you think its just some dirt between the rotor and pad?