Do I need a new brake booster?

hey fellas, i recently acquired one of our more 'vintage' xj's(read worthless bag of monkey turds floating in thousand island salad dressing)
not my first xj, of course, but the first time i've had brake problems with one. it was fine when i first got it, but had been sitting, so i drove it for a few weeks, and now the brakes feel spongy, and the motor won't idle right. if i disconnect the vacuum hose going from the intake manifold to the brake booster, the motor smoothes right out, and as expected, the brakes get real hard to push.
could something just be stopped up that i could clean out? the little valve on the end of the vacuum hose seems to do what it's supposed to- lets air flow one way but not the other. it's not super easy to blow through, though.
ideas? not feelin a booster swap on top of all the other things i'm going to have to do to get my little beater going again.

It seems the booster has a leak and needs to be replaced. Sorry.......

^that sucks.
i tried to pull the hose off the booster with the engine running, and it was hard to do because there was so much vacuum. like it made a hissing noise when i pulled it off. i don't think it's a leak so much as something is plugged up.

if i pump the brake pedal at idle, the idle smoothes out?
i dunno, i'll prolly drive it without power brakes for a while if it really needs a new booster, because i'm seriously broke for the next few months(laid off), and currently mooching off my wife (of only one year, so this would be the 'poorer' part of the richer or poorer thing) which she most likely won't be cool with for very long, lol.
i bet i can get a used one for free from somebody if i have to, but yeah, it's not acting like the last brake booster issue i had(84 firebird), where the pedal was just really hard to push all the time all of a sudden, but the motor still ran fine, so i'm hoping it's just plugged somewhere.

here's to hoping that all of our jeep problems are cheap and easy to fix! :cheers:

Depending on the year, (hint...you didn't post it) there are single and dual stage boosters. The dual stage booster actually has to have a good seal against the master cylinder to work correctly. Hopefully that is your problem.

ha! i apologize. it's a 1984 4 cylinder, 5speed, 4x4

Definately a single stage booster.

yup mine too lol wanna upgrade to a dual but dont know if i will need to shim it or what??

so replace then? that sucks. definitely gonna be a junkyard item...