Brake warning light on?
Any smashed lines under the car? Sometimes someone will take a little off-road excursion and mash them up. But the pedal would probably still be firm even if.
Lumina, like most FWD cars, uses split diagonal braking system. Each chamber in the master operates one front and the opposing rear brake.
Have to bled in sequence, or you just chase the air from place to place, never comes out...
http://repairandshare.com/car-brakes...ng-the-brakes/
Here's a reference...