It a 1965 barracuda with power brakes. Just replaced the master cylinder. The engine idle drops a lot when I press on the brake. This car has sat for 34 years. I suspect the power booster is leaking vacuum. Suggestion?
Disconnect and plug the vacuum line going to the booster. Doing so should drop the idle to where it is when you press the brake. If so, then you have a vac leak in the booster or at the grommet holding the check valve into the booster body.
