I've been noticing lately that when I hit the brake lightly, I can feel it losing pressure very slowly, and if I sit there and push slowly down on it when I'm stopped, it will eventually go down to the floor.

No leaks in the lines, and I've bled them already. When I'm idling, if I push the brake pedal down and let up, it will go from idle up to about 1300rpm, then fall back; which leads me to believe the booster is going bad.

Help is appreciated...

 

thats what it sounds like. There is also a rubber gasket that goes in between the master cylinder and the booster. i would check that also before buying a whole new booster. also check all the vacuum lines

 

do u have the check valve on the brake hose from the marter cylinder and the intake manifold