Welcome aboard!
Don't mess with the IACV. Have you put an OBD scanner on it?
A vac leak is likely, but there's a possibility of fuel pressure issues as well. Fuel filter?
Vac leak won't be audible, use starting fluid or a smoke machine to find leak. Z32 engine bay is a cluttered mess, so to think you'll easily see or hear a vac leak is... well, funny.