brakes acting up at first

[badbusiness75]

how's everybody this mornin? hope everythings goin good. gotta little problem i'd like some help with. when i first start up and drive in the morning or after the truck has sat for a while, the brakes do not engage until the pedal is halfway or all the way to the floor, and when they finally do engage they are full on and lock up. so it goes from no brakes to full bore in an instant. also have a hissing sound coming from the floorboard around the pedal when the brakes are depressed. is this an abs problem or a vacuum problem, or both? am i on the right track?

[badbusiness75]

i should also say that it goes back to normal braking after a few stop lights, but the hissing sound remains.

[cdnsarguy]

Do the vacuum test on my gallery.... it should show up the problem(s) Are there any lights on IE brake or ABS....

Please put up a signature with all the truck info......different years different problems.

[badbusiness75]

oh, sorry. its a '94 f250 4wd w/ abs, manual, 7.3L IDI