Good evening,
First of all if this is the wrong place to post, please say so and I will go where I need to.
I have searched and can't find an answer so far.
I have a 2008 Chrysler Sebring LX 2.4L 4cyl.
*** When I apply my brake, the rpms increase by about 500-1000 and then immediately go back down to normal. Other than that, there are no issues. I was told it was downshifting and it was normal.

Any advise is much appreciated. I sure hope I didn't purchase a big headache.

Please help

 

The usual cause of fast idle is a vacuum leak. The power brake booster is powered by engine vacuum. I would start looking at the vacuum lines leading to the booster, also at the check valve and maybe the booster itself.

 

Thanks for the response. I looked at it more closely this morning. It only does an increase of about 250-500. But in a complete stop it idles perfectly at 750-800. Does this still sound like the same problem? Is what you talked about earlier an expensive or complicated fix?

Thank you

 

If it does it while you're moving, slowing down specifically, yes, it's downshifting and is totally normal. The engine has to downshift so that engine speed can be maintained. It's the same concept as pushing in the clutch and shifting down in a manual transmission.