abs braking problem

[spare79]

1996 explorer XLT V8 AWD

when applying the brakes under normal road conditions, the pedal vibrates as if the abs system is engaging and the pedal pushes down like there is "no resistance". it does stop but does not stop immediately like it is suppose to.

any ideas what could be causing this to occur?

 

[swetrid]

Could just be a brake vibration due to warped rotors. When speed does it do it?

 

[spare79]

to my knowledge it occurs at low speeds. it also makes a thumping/vibrating noise when it occurs. is it possible that its an ABS sensor or unit itself?