need help with brakes

removed calipers to paint…after install and bleeding my pedal was sinking to the floor…i thought that maybe after bleeding and putting in new brake fluid that maybe my dot 3 cleaned out all the gunk in the master cylinder and the seals were not holding no more, so i changed the m/c…problem is still their any suggestions?!? maybe brake booster?!? i doubt its because their is air in the lines…cause i bled the ish outta it…or are the abs models harder to bleed?!?

thanx for any help