Brake rattle i have a 2005 mercury mariner recently i changed the front brakes new rotors and pads . now only on the front passenger side i hear and feel the brake rattling when i slow down to stop .

Something has broken. Remove tire and inspect. I have seen brake pads come apart and move up against the rotor.

check and or replace front rotors and pads shaking under braking usually points to warped rotors --

If you have access to a lift put it on and look at the area where the noise is coming from if you have a small camera try and put it somewhere you may be able to see what it is doing.
Good luck.

It's the pads rattling around in your Caliper is if the noise goes away if you have your foot lightly on the brakes

Possibly a bad wheel bearing. Brakes would get louder as you apply the brakes.

anti rattle plates are damaged, remove pads clean rear surface apply thin layer of silicon to pad allowing it to dry then reinstall as per std, this will stop the squeak, or replace anti rattles, silicon is cheaper will last the life of pad, but all new pads will have to be treated the in the same manner .

Check and see if the Brake Pads were re-installed with all the hardware, ie, Anti-Rattle Clips, shims etc. if your pads are not secure in the Calipers it will cause the pads to rattle when you are driving in effect causing your brakes to make weird noises, ie, groaning, squealing, rattling.

The tool is nothing more than a 3/8 drive allen hex head, metric. They come in a set with 4 wrenches, sized from 7 to 10 mm. and 4 inches long just for brakes. Sears has them I think. Your Ford has different size bolts front and rear. The set is only about $8. Get the pads done before they eat the rotors, I hear they can't be turned, which is a joke. Hope this helps.

Could be just a sensor dirty, or bad connection. Who did the brakes?

jc whitney's front pads: http://www.jcwhitney.com/SATISFIED-PRO-CLASSIC-BRAKE-PAD-SETS/GP_2009480_N_111+2006+200732167+600001068_10101.jcw Rear shoes: http://www.jcwhitney.com/BRAKE-SHOE-SETS/GP_2008466_N_111+2006+200732167+600001068_10101.jcw They've got rotors if you need them too.. k