I have already bled brakes and changed the master cylinder. What would be the next step to try to fix the brakes. The brakes still go to the floor.
Turn the car on and press the brake to the floor. When you release the brake-- listen for a kind of hollow wind sucking in from under the dash. If you hear a hollow sucking noise it means your Power Brake Booster is failed and you need to replace your Power Brake Booster. The noise can be faint or close to none at all but if your pedal is still going to floor after changing the Master Cylinder then it is likely that the Power Booster is gone.