2003 econoline con van 4.6l. Pedal is going almost to floor with engine running. Pedal is firm with motor off after about 1/2 inch travel. Held pedel to floor and shut off the engine and pedel pushed back up. Disconnected the vacum line to the booster and pedel is firm with engine running. New lines from master cylinder to all wheels, New master cylinder, new wheel cylinders, ABS box in engine bay was bypassed (not sure of the proper name but its what the lines run into from the master cylinder), have put at least 4 big jugs of fluid trying to bleed the system and it's still not engaging the brakes till the pedel is almost to the floor. Am I looking at a bad booster?

 

Turned out to be a bad booster from a faulty master cylinder. Brand new master leaking into the booster caused the diaphragm to break.

 

Thanks for the update.

 

I know my grammar isn't perfect but I hope it helps someone out there that might run into the same problem. Not much info out there about the econoline van that I could find.