My 7D was all over the place with focus... just terrible depending on the lens used. Making things worse, one lens, an old EF 28/2.8 was a "poison lens". Once that lens was mounted, everything after that, regardless of the lens used, was out of focus by a whole lot. From removal of batteries and complete reset, most lenses had focusing issues, but they were just a little soft. After the 28/2.8 was attached, all the lenses would be out of calibration. They seemed to do ok at about medium distance, but were way off at infinity and way off at say, four or five feet. Things went to front focus to normal, to back focus --- from far to near.
Since the lenses worked fine on the 5Dii, I just sent the camera to Canon. They changed a lot of stuff, new focusing sensor, new card slot, new release button... and one other item. Whatever they did, it came back great. Some lenses still need AFMA (camera seems to front focus a bit) but its correctable with only a few units of adjustment on any lens that requires it. And, the 28/2.8 while not a super great lens, is no longer "poison" on this body.