Odd acting brakes
 

Hello all
First off I want to say my truck isnt throwing any codes, nor am I loosing any pressure on the brake peddle.
What is going on is my brakes are working just fine I can stop from any speed and my brakes are performing just fine until I slow to about 5mph.
From 5mph to 0mph it almost feels like I slide on ice for a second, and you hear a sound almost like what you hear when your ABS kicks in. I will feel a slight fluctuation in the brake peddle and then my truck comes to a stop. It is the darnest thing. It happens everytime I brake. One machanic I spoke to said he thought is was the vacuume sustem, another thought it may be the brake sensors....
Anyone out there ever have this?
Thank you
Ed
2003 F350 4x4 quad duel 35,000 miles