RPM drop with brake applied

[Ozy44]

When I apply my brakes at a stoplight my RPMs drop by about 80. I have tried stopping at a light slowly using the e-brake and I do not get the drop. Does this indicate that I am having a failure on my brake booster or just a general vacuum leak somewhere. I checked the brake booster check valve and it is operating as it should. I also do not have any vacuum sounds inside the cabin when I press the brakes. Could some other component of the brake system be causing this RPM drop? The RPM drop causes a pretty good shutter at stop lights when the brake is applied. I'm currently at 167,000 mi on my 2012 3.8

 

[Carr.patrick87]

I had this problem and what i found was the my break booster line was clogged due to my brake booster being worn out and leaking. I replaced the brake booster, brake booster line, and the master cylinder and that fixed it.