Inconsistent idle when cold

Hi,
Can anyone suggest some troubleshooting for this up and down idle when cold?

It's an 8v Digifant PB Engine

(please ignore the tappity tappits)

https://youtu.be/o7lijn5Oz8U


 

I think I answered my own question, I remembered I bought an Idle Control Valve years ago (didn't know that was what it was called), I've replaced that and it seems much better.
Idles a bit high, but better that than the up and down thing

The old valve is pretty oiled up inside