Need help with braking problem

[Blindedlegacy]

I was driving along one day and i went to press the brakes and it was firm then i let go of it a bit then went to press it again and it went to the floor before i got some real stopping force. now recently it just goes to the ground. ( as im pushing it to the ground im getting some stopping force but not alot.) My first thought was i need to bleed the brakes and i did it once without a one man vacuum bleeder then on another day i did it with 2 people. Both time no air came out and the pedal was firm at a stand still but went away first time the car goes into motion. Then i decided to replace all 4 rotors and pads, and the problem still remains. this issue is annoying the crap out of me and i cannot figure out what it is plz help me