2006 Subaru Outback rough idle and stalling

Any leak at the intake manifold will not show up on a compression test. If there is a head gasket problem that caused a breach into one or more of the combustion chambers then yes, that will show up.

While it varies a bit, the numbers you’re looking for on a compression check should be in the 175, 180, 190 PSI range and all numbers should be fairly close to each other.