A vacuum leak would cause a uniform problem across all cylenders, or at least on whole bank on a v8.
If you have two that appear fine, either you have problems there that will show when the vacuum is fixed, or it wasn't vacuum to start.
Low fuel pressure would be caused by something in the fuel system, not vauum. It either an electrical gremlin, or a mechanical failure. A vacuum leak may cause a lean condition, or a rough idle/acceleration, but shouldn't result in low fuel pressure.
2002 BMW 530i
1997 Ford Mustang GT
1995 Honda VFR 750 (For Sale)
1964.5 Ford Mustang