Car cuts out whilst starting a couple times and also because if being revved fully after starting?

So yeah, it does that from starting cold i think. It has been suggested that its my Idle air control valve but i've cleaned that out and it still does it. Also replaced spark plugs. Its a Ford Fiesta 1998.

However, it idles fine as soon as I've moved the car. So even when stopped it is fine as long as i have driven it since start up. The issues only happen on start up. Any ideas?

Fuel injectors might be sticking or the car is not building fuel pressure fast enough on startup. Have the fuel pressure checked in your car to see if it's within acceptable ranges when cold.

Possibly a dirty throttle body plate /bore area is altering proper airflow for the computer to set proper IAC settings for proper cold idle.

How long ago did you clean the IAC? Make sure to clean the passage in the TB that the IAC tip sits in which may still be crudded up.

It may take several cycles of starting the engine cold and allowing it to warm up and drive before the computer recalibrates proper IAC settings for a cold start idle speed.

As the IAC gets dirty over time and crudded up, the computer has to recalibrate how far the pintle tip moves or opens up to adjust for proper idle speed. When you clean the IAC or replace it, the computer then has to recalibrate it's position setting for the IAC which will differ from previous memory settings which can lead to periodic stalling or idle speed issues until it recalibrates. Or you could have other issues with a bad /defective or sticky IAC, etc.

I would also clean the TB plate/bore area and linkage and clean the MAF sensor… Special spray cleaners fro them sold at parts stores… Which can get crudded up with soot and carbon over time and affect proper idle airflow or computer readings. Disconnect the battery cables from the battery for around 10 minutes and then touch the ends together briefly… Which will reset the computer KAM memory… Reconnect the cables to battery and try starting… Cold engine.

You may possibly also have issues with fuel system pressure dropping overnight or sitting for long periods from a leaky injector, etc… Might need to test for proper fuel pressure.