As far as I know, you should not have any open leak anywhere in the vacuum system. I would try to repair any cracks or breaks, rather than plugging them. Just my 2 cents.
95 Contour Zetec, ATX (wrecked, sitting in the barn)
95 Mystique Zetec, MTX
2000 Taurus SEL 3.0L Duratec
1994 Crown Victoria LX 4.6 V8
1993 Chevy Silverado 4.3 V6
| 
