I've replaced the master cylinder, both front calipers and new brake pads, and my pedal is still soft. I know the calipers and pads wouldn't have anything to do with it just throwing that in there, but it was bench bled and and bled on the truck and bled all the air out the lines, and still have a soft pedal. And as a last resort I adjusted the bar on the brake booster and still nothing.

Any ideas?

This is on a 98 4x4 f150 4.6

 

Just because parts are new, doesn't necessarily mean they are without defect. Double check that master cylinder...

 

If you don't have metal braided lines going to the calipers, they may be stretching when you apply the brakes. If not that, you probably still have some air in the system. Did you keep the master cylinder full during the bleeding process?

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when you installed the new calipers - are the bleed screws on top or bottom???

Common mistake is to put them on the wrong sides.

Bleed screws should be on the TOP!