I have a Basket case 99 5.2 RWD (rear ABS)that was sitting for five years and had a hard 157k on it. When I first started driving it with all of the old components, the front brakes would smoke and there was extreme heat at the wheels. The brakes were beyond shot with very bad fluid, so I just chalked it up to worn out parts and replaced: rotors, calipers with new pins, master cylinder, soft lines front and rear, rear wheel cylinder, rear pads and new hardware for drums. Bled two times and master was bench bled.
I though everything was ok but after driving it a few times on the street the smoking is back along with the smell and after barely getting it back home, the fronts seem to be locked up and it felt like the rears were as well.

Right now I’m thinking proportional valve, and I’ve heard booster maybe a problem too? What are your thoughts? Really want to keep the throwing parts at it to a minimum if possible.

Thanks.

 

Usually, that kind of behavior is the soft lines, or seized calipers. Proportioning valve won't do that. Jack up the front, pull one of the wheels. Turn the rotor by hand. Does it turn easy? if it does, stomp on the brake pedal a couple times, if the rotor will NOT turn now, crack open the bleeder valve, see if the rotor will now turn. If it does, you have a blockage in the line somewhere. If it doesn't, then the caliper is likely at fault. (or, the guide pins...)