brake power loss at low speed on 2001 Ford Explorer Sport Trac

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
When braking truck slows to 10-5mph and brake pedal travels a bit (like a pressure loss) and you feel what seems to be a grinding noise . I think it may be the booster or master any ideas. Fluid checked and all brakes newer just had new upper and lower balls done ABS light is intermittent
(3) Answers
Could be the master cylinder failing but usually this is what happens when the brake pads are worn out as the caliper is trying to stop the vehicle with very little friction material left, this happened on my Durango even though I new it had new pads my wife worn them out in under 10,000 miles
just had simialr prob on mine had 2 put new bearings in front with sensors was causing the breaks to not work right cost about 650 to fix that included labor