1999 Dodge Caravan Brake Problem

Brakes problem
1999 Dodge Caravan V8 Front Wheel Drive Automatic

before I replace the brake pads, rotor, calipurs, my van would slow way down brake pedal would get tight wouldn't even have to brake the van would slow down to a stop, took to mechanic and he said nothing wrong, but the pads were woren down to just about nothing calipur had a broken piece so replaced it and the rotor were in bad shape so replaced them, got the brake job done and everything seemed fine till I drove it again and it seemed the brakes locked up they got really hot threw snow on the tire to cool off brakes, let van sit for hour and then drove it back to the work shop no problems going to check the work again, hope u can help me thank you