Little brake pressure when running

2008 Tundra extra cab, tow,4x4,5.7, auto, tow pkg. Decided to redo brakes as I'm now towing a 7k camper. New front rotors, hubs, calipers, brake pads, and brake lines. Bled front wheels all air apparently removed.
1. When not running brakes are firm and a wooshing air noise can be heard when pressing the brake to the floor, resistance is there, can press to the floor as many times as I want but the air noise is evident.
2. When truck is running the brakes have very little resistance and it cant be built up by pumping the brakes, no air noises.
Next, I will bench bleed the master cylinder, check the booster brake valve. If this doesn't solve the problem am I resigned to replacing the Master cylinder? Brake Booster and the ABS?
I hope someone has a simple fix, $$ is an issue for me presently .So if anyone has a suggested order of repair or something I missed I would appreciate the feedback. Thanks, Dinty

 

Seems like there is air in the lines to me. With all that you replaced, including the lines, I think it would make sure it is bled well first. If you were not having an issue before, I can't imagine the master or booster would all of the sudden have an issue.

 

Welcome aboard from SoCal.

 

Welcome