Idle Speed Stabilisation Control Unit is its name apparently.
Its in the centre console near the gear stick (i think).
I'm sure its in Haynes as thats where we found it.
Regards,
Justin
BTW. Not sure if this is correct.
On the top of the engine where the throttle presents itself you can do the manual bit and rev the engine, but in its idle position there is a dip switch.
I was told many years ago, that when in this position the engine management unit puts the engine into the idle mode.
However, whilst the engine is cold the idle speed is controlled by this electrical unit that may of broken. Once it comes up to temperarture the little dip switch and EMU take over again.