Sorry to say it would of been running lean when on-boost 'IF' when it was mapped the hose was in place.
With the Vac attached, as boost rises so does the fuel pressure i.e if at Idle and approx -0.5bar vacum the fuel Pressure is 3bar, then at 1bar boost fuel pressure will be approx 4.5bar. With the hose off it would still be sat at the idle level regardless of boost.
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