duckie does the pedal almost go to the floor with engine off?
hydroboost may be your problem...but you could have frozen caliper slides, soft expanding brake hoses, soft cheapy brake pads
did brakes work properly then all of a sudden begin with this problem?
If it is a class C and has sat for a while...they are known for sticking caliper slides due to water off on the frt corners of the roof
04 D-Max Crew Dually
96 Monaco Dynasty 36'