I have a 2001 2wd 3.0 does the same exact thing....rotors and pads are perfect/worn normal, have newer rear brakes....i cant figure it out...new calipers helped for a while, an alignment helped for a while.....my alignment didn't hold very well which led me to wonder if something is warped or bent beyond holding an alignment ,thus possibly being my problem, but what's grinding??? I've also thought that since i have new calipers,rotors,pads that maybe its a brake line not flowing properly TO a caliper, theres two cylinders for each caliper on mine.. maybe if one cylinder is coming and going in and out faster or slower than the other, the pad gets pushed unevenly and somehow wobbles into a position that it grinds against something ?? I see no grind marks though on ANYthing, it's really weird, makes me wonder about my rears but they are newer and good also.....only thing left maybe is wheel bearings, my thing happens when i have to brake somewhat fast, firmly, and comes near the/at the end of the stop.....maybe the bearings can handle everything but a quick firm stop? I have the new bearings, seals, grease, ready to go just need to get around to doing it, .....symptom hasn't happened in a few weeks.....