Evening chaps. Car is a Focus 1.8 Zetec.

Basically on cold start it goes a bit like this:

1) Crank for usual duration (around 0.5-0.8 secs)
2) Fires straight away revs up to around 1300rpm

3) Issue starts here. Should settle at around 1000rpm or so but it doesn't straight away. After it fires and revs to around 1300rpm the revs drop to like 600-700rpm then suddenly it kind of thinks "oh wait a sec, I'm still cold, more revs)"then it idles normally. But then sometimes it tries to drop the revs back down again and immediately corrects itself after it realises it is still cold.

Today problem kind of escalated. Fired in the usual way then tried to idle at its normal idle pace and spluttered quite a bit and hunted till the ISCV thought "better pick the idle pace up a bit now this doesn't seem very smooth" and again idled OK. Once or twice it has actually stalled from not being able to pick up the revs but hasn't done that for a while now. If you restart it though straight away it behaves like normal no hunting at all.

So far have changed the MAF, cleaned my induction cone, cleaned the ISCV which is new anyway only done about 4000-5000 miles on it and checked the PCV valve and piping. I'm thinking because it is only a cold start issue and let me note it isn't every time sometimes it won't do it at all and sometimes the splutter is only tiny, that it could be related to the CHT sensor. Thing is this was changed about 10000-12000 miles ago so it is making me think that it can't have gone already or something is giving it duff readings for inital cold start.

Anyone else have any advice?

Cheers!