Did you bleed the RABS valve on the frame? If not the order is RR, LR, RABS, RF, LF. I think I would also try to tighten up the booster actuator rod to MC clearance as well. The only thing you haven't replaced is the RABS unit. (And it does sound like the Cardone booster was leaking from your description).

Presumably you do not have an abs light on. If you do, you need to pull the codes from the orange/black wire hanging down near the parking brake pedal.

https://www.f150forum.com/f10/how-re...e-codes-62106/

 

I had the exact same issue with the brake light not coming on and pedal going to the floor almost, my mc was pitted badly, changed that and it helped a bit, made sure the rears were well adjusted and everything was new about a year or less earlier. Ran a gallon of brake fluid through everything and still not better, bypassed the RABS valve and no difference.

It ended up being the front calipers, it was hell to get the pistons out and when I finally did get them out I had lots of brake sludge,

 

The front brake calibers are almost a regular service item on these trucks, especially if they are not driven all that much. I'm on my third set counting the factory ones.

I also had to replace the rubber lines as they still looked good, but almost zero fluid could pass through them. I had the symptom of one caliper wanting to drag and a mushy pedal that got hard when trying to stop.

 

I did bleed the RABS and in the order that you've listed. Unfortunately also, My front brake calipers were replaced along with all of the lines/hoses and pads. Not sure how many more options I've got