My wife 2004 Buick century has a problem with its brakes.

What is your question?

You push on the brakes and they work fine but as soon as you take just a little pressure off of the system, The pedal wants to go to the floor. Don't no if they need to bleed or not, I don't see any sign of leakage around the master or slave cylinders. Wondering if it could be the power booster or the control unit that is run by the computer for the ABS and anti slip traction. Please if anyone has any idea what could be going on please let me no. Just hope it is something that I can do my self and not have to take it to a dealer. Thank you all and good luck on keeping your cars going for a long time. Billy