Try back bleeding it, get one of them squirty oil cans, fill it with brake fluid, put a bit of hose on the end of the nozzle and attatch the other end to the bleed nipple, crack the nipple off and pump the trigger on the oil can, whilst you pumping the trigger get someone to watch the the resivior closly and see if the level rises and see if any air bubbles are rising up through the fluid, but before doing this make sure u havent filled the resivor to the top or ull make a mess, once the air bubbles have stopped coming uo through the resivior tightten the bleed nipples back up, see if the pedal is better and if so bleed it normally (like u had been doing) Hope this helps