Hey guys. I have a 96 xj 4.0HO

When applying the brakes and coming to a complete stop my idle goes down to the point my jeep almost dies. I have changed every sensor in this thing in the past year so not sure where to start. Throttle body is clean and I just put a new IAC in a couple weeks ago.

I replaced the header and put a new intake manifold gasket on. I thought it might be a bad vacuum leak but have searched all over and can't find one.

I am going to order a new brake booster and try that but from what I've read mine doesn't seem to be leaking.

Jeep has 185k miles so I don't care about replacing random parts. Any suggestions would be great. Thanks!

 

Does it do it with your foot off of the brake?

Test your vacuum first. Buy or borrow a vacuum gauge. Pull the brake booster hose at the booster and use it for the manifold vacuum source. At your lower than normal idle you might be somewhere around 17. Giving it some light throttle should put you 20 or more. If not you probably have a leak somewhere. Although the timing being off can affect the vacuum to.

Almost forgot. If you haven't already replaced the CTS pull yours and polish the probe.

 

It only happens when I hit the brakes. Right when I come to a complete stop is when it happens.

I was told that if there is a big vacuum leak it will be most noticeable when hitting the brakes since the booster uses so much vacuum. I'll get the gauge to check for the heck of it. How much vacuum should it be pulling with no leaks at a normal idle?