If the pedal is mushy even without vacuum assist (engine off) and goes clear to the floor, IMHO
1) your bleeding is not complete, or
2) you have a bad caliper, or you have a bad master cylinder (even though new), or
3) you have a swelling brake line probably ready to burst.

Brake bleeding without assistance is not the easiest exercise. Personally, I have found that since I bought one of these, it is one of the easiest jobs to do on the truck. My brake fluid is always fresh because I actually bleed the brakes annually now!

Some use vacuum bleeders, but I see issues associated with them (sucking in air, etc.). Can't beat the Motive unit IMHO.

HTH,