Brake Pedal Goes to The Floor

Car is a Sebring convertible JXI. Just replaced all four brake pads and rotors that were in poor condition. Brake pedal was spongy before the parts were replaced. After replacement, the brake pedal would go to the floor with the engine running. Decided to bleed the brakes. Bled 1.5 quarts throughout the brake system to include bleeding the master cylinder. Got a hard pedal when engine was not running. Soon as the engine is running the pedal goes to the floor. Tried bleeding with the engine running and saw a very mild improvement, but still goes t the floor. Many thanks for your assistance.