Set the combo on good heavy tripod, turn VR off, as well as AF. Choose a easy readable target, focus manually, use MUP and remote or cable release. Open the lens wide. Set shatter speed not less than 1/1000. Do not touch anything, remove the card, watch your target at 100% crop. If anything is wrong - say, more than 2-3 images, from 10, you need glasses - I am serious, even if Live View in use.
If nothing is sharp, this is the lens fault. If everything is sharp, adjust the Fine Tune for your combo, nothing else you need. Good luck! LZ