The iscv sounds lazy, but can usually be cured by cleaning with carb cleaner, it should be fairly easy to spot having most likely a two wire connection to it, and be cylindrical in shape about 1/2 it's length on the inlet trunking somewhere.
Put the engine details into ebay etc with idle speed control valve, this will bring up piccies showing you what it looks like, then easy to find.
It could also be the lambda/maf at fault, but clean iscv first, it's almost free!!
tabetha