Re: 2000 Lincoln Town Car
Why do think it's a vacuum leak? If so it should be easy to find by tracking down the hissing sound from the part that might be leaking. Use a technique similar to what a doctor does with his stethoscope. A piece of hose near your ear and the other end probing around the various vacuum parts and tubes will help locate the vacuum noise. (engine running at idle)
On the other hand you might also have clogged part not allowing vacuum to pass. A common problem is carbon build up in the EGR where exhaust gas is used to blend with the air from the intake. Using a code reader will help pinpoint this.