Not my truck, its for a freinds mom.

97, 2wd, v6 vortec, 43K miles. When you apply the brake, you can hear a hissing sound. The brakes are not very good, and it takes a while ot stop. Pedal is pretty stiff. If the truck is in park and you hold the brake pedal down, after 15 seconds or so, the idle of the truck fluxuates. If you remove your foot from the pedal, the idle is fine.

Is this a power brake booster (not sure if that is the actual term) issue? Ive never worked on one of these trucks before.

thanks in advance.
dave

 

could be the booster itself or a vaccum leak