when you push the brake peddle does it slowly drift, or is is really soft? if its just soft it is possible that you did not get all the air out of the lines, or the rubber lines that go to the front calipers could be close to blowing. They will swell under pressure. If you peddle slowly drifts to the floor it is possible that you have a bad master cylender. Even new ones can be bad. Have you checked your rear wheel cylenders to make sure they are not leaking? If you front pads are frozen in the calipers that will also cause a low peddle. make sure the pads move easily. hope that helps a little.