I'm in the same boat as you are. My girlfriends Accord is having the same problem, it's a 91. When you sit at a light in her car, the pedal slowly sinks to the floor. I bled the brakes today, no air bubbles, and there is plenty left on the pads and rotors. I'm guessing master cylinder or brake booster is going out. There aren't any leaks so that's a good sign.