it should be 38-ish with the vac line off (and vac line plugged - Michael Yount can get into the semantics of how the vac leak changes the setting oh so slightly [leak = higher idle and unmetered air = off by a smidge: ) ].
most run at ~32-34 psi with the vac line on at idle (depends on the amount of vac you have, etc). a clogged filter is definately something to check and replace (i would just replace it). the pump can be on the way out, as can the regulator (which will toss too much fuel back to the tank and result in low pressure).