Could be as simple as a vacuum hose fell off.
Look around or find a way to put a short blast of air in the vacuum system, or have a garage do a smoke test to find the leak.
185k, 5/20/12 new ej257 short block, 8/20/11 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
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