Pulsating Brakes

I Tried this on the Mercury Sable Site but no replies, I also looked on the Ford Taurus archives and found nothing, I am completly confused, and I thought you guys could help.
My Girlfriend drives a 1994 Mercury Sable that has front and reart disc brakes. The problem is when she goes to a stop, some times the abs will feel like it is kicking in and can make stops really dangerous. I noticed it really doesn't matter what speed the car is traveling at. It also doesn't matter how hard you push on the brake either.
I have just replaced the rear pads, calipers, and rotor so I know they are not the culpret. I dont think it is warped rotors, because it really feels like the abs is kicking in. Is there a way to test the abs sensor or can they be cleaned some how.
Any sugestions would be great.

4SnowandRally,
Your problem sounds like it needs to be looked at. There is a site manned by over 1000 technicians: www.batauto.com, might get a response there.

Willyum
Thank you for the tip on the other web site. I just purchaced my first house and money is tight and I would like to waite on taking it to the dealer untill last resort. Once again thanks for the web site.