Q: Car stops slower & brake pedal goes to floor

I noticed that my car was not stopping as quickly as it used to. Plus, my foot goes down farther on the floor than it did before. My neighbor took a look and saw grooves on all four rotors, so we replaced those and also the brakes. But I still couldn't drive the car; it still had the same stopping problems. Plus, the ABS and brake warning lights came on. By putting in ABS rings, the ABS light went off. We also worked with the e-brake cable and that shut off the brake light. But the brake pedal Still goes to the floor.

Next, we examined the master brake cylinder and the rear calipers. Bled the brakes and now all four brakes have pressure when the car isn't running. But once I turn on my car, the brake pedal goes down to the floor. We have not tested on the road to see if this happens there. This stopping problem had started about two weeks before the brakes and rotors were replaced, and it only happened with quick stops and after it rained. Can you direct me to what needs to be done to find the solutions for this problem? Thanks.