Brake vibration

Hi folks. I own an '05 V8 , and the brakes, front I think, are grabbing when I brake. I thought the rotors had warped, so I pulled them off & had them machined. All was fine @ first but then the grabbing started again after several days. I'm stumped!
I'm going to buy new rotors & pads on Mon. but I really hate throwing parts @ a problem when I'm sure . Any thoughts?

 

either the pads need to be fitted better( by that i mean filed so they can move a lil) and pad guide pins greased, or your brake calipers are shot

 

most likely the calipers

 

Calipers for this model 4runner has a known issue of the piston seizing up in the caliper. I replaced three calipers on mine.

 

calipers last about 2 years in northern mi