I replaced the rotors on my 2001 ford explorer sport and when i went for a test drive i hit the brakes real hard and after that when i hit the brakes real easy the peadel goes down and the brakes makes a rumbling noise and it hardly stops but when i drive it like normal its ok until ii get to a red light and almost stop it feels like it just turns loose some and the pedal goes down and barely stops what could it be

SOURCE: brakes

This seems like two different vehicles with two different problems. first the 1997 Ford Explorer- with new rotors and pad. I can almost guaranty that the rotor and pads that were replace are "after market" parts. If it is true,then the brake pad are at fault 95% of the time, the other 5% is the rotor. This because alot of after market parts are alot cheaper and are poorly manufactured out of cheap materials. I would recommend Motor-craft rotors and pads for this vehicle and that would take care of this problem. However if it is original parts on the car the dust shield on the hub may be to blamed, may have gotten bent into rotor during brake job. As far as ABS re-learn braking pattern that all BS that's absolutely 100% NOT TRUE. I am ASE certified in brakes and I never heard of such nonsense. As for the 1999 Explorer this problem is the ABS system applying it self prematurely. The sound that you feel on the pedal is when the ABS is active. Most common reason for this is a bad abs/wheel speed sensor, it could have gotten damaged during the brake job or grease or rust or something is between the sensor and sensor gear/ring. I have seen this many times before, just re-check everything. The abs becomes active because it detects a slip or brakes locking up or in your case maybe a false reading from sensor. Good luck and contact me if you need more help

SOURCE: brakes

you may have to take the rotors back off completely and look for the baby brake shoes behind the rotors because sometimes they will hang up and give you some of the problems you are having

SOURCE: 2002 ford f350 deisel brakes pedal feels hard and

You should have a hydraulic brake booster. a common failure item on fords and also would cause your symptom. the burning smell, I would go back and recheck all the brakes. Maybe a problem with the e-brakes, or an issue with the front or rear calipers. Possibly a damaged steel or high pressure brake line. Good luck.