I have an 89 GT that i recently rebuilt. the car sat for about 2 years and now that i have it running again the brakes are bad. i noticed that the fluid was low when i went to start the car for the first time so i filled it up. ive bled the lines and replaced the master cylinder but htey still seem to be bad. the pedal will go down half way before it does anything and then it seems like its just the front brakes. any help would be greatly appreciated.