For some reason my 99 gmc kind of stalls
and begins to run like it wants to die while
the brakes are pressed idels normal any
other time only acts up when I apply the
Sounds like a brake booster leak if you have standard power brakes, if you have hydro boost brakes it could be the idle up system, it is suppose to bump up the idle slightly when the brakes are applied, but it is only the hydro boost system that has the idle up.
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