Is it my brakes or vacuum leak
Do you have brake fluid in the reservoir?
If you lost vacuum it would affect the booster, the brakes themselves are their own system, you would still have brakes but they would be much harder to press. Check the check valve on the booster if you think you have a problem with vacuum. Otherwise check the master cylinder.
Ok thanks we are checking the booster now.
Looking for a Used Mustang in your area?
CarGurus has 1,221 nationwide Mustang listings starting at $3,995.
Search Ford Mustang Questions
Ford Mustang Experts
Related Models For Sale
Used Cars For Sale