the original spec is 1000 plus or minus 50 rpm. 750 without.
im guessing that there is something wrong with your air conditioning that is putting a strain on power forcing the idle up to compensate. unplug the ficd electrical plug. it might still have a staple so remove staple first. it is the first plug you see when looking at iacv.
1989-1998 240sx TUTORIALS
FACTORY SERVICE MANUAL
Factory service manual2
Factory service manual 1989
Old FAQ
INSTALLS
Pictures of parts