I recently replaced the rear brakes on my '92 Corsica. I bled the brakes the same day. Since then, I've noticed that the brake pedal is soft/spongey when I go to shift from Park to Reverse/Drive. After I start driving, the brake pedal gets firm. The level of brake fluid in the reservior has stayed the same. I'm just curious what might be causing this. Any ideas?

 

Sounds like air in the break lines.

How did you bleed them?
It is a 2 person process.

"Open, then push peddle, then close, then release peddle, check fluid level after 2-3 times."

Also, My car had a failed master break cylinder, it would not push any fluid through, kinda acted like spongy breaks, but defiantly would not stop the car.
But it does not sound like yours. The way to tell is when bleeding the breaks, does fluid squire out with force?