Poor idle cutting out - mk2 focus 1.6 petrol

[newuserhere]

So it idles quite rough. Press throttle to 1k rpm and ok. When cold it naturally idles at about 1100 so is fine and when you rev falls back to that so is fine.
When warm if you rev it then let it fall to idle it often falls to about 600rpm and struggles then idles rough at about 900.
Often it will fall so low it cuts out.

Makes it undrivable as if i try coast or drop clutch to stop at roundabout it cuts out.

Rev it's bks off and smooth as hell.

I've replaced throttle body (electronic) which also controls idle. Replaced map sensor. Removed and blocked both vacuum pipe slots and breather slot on manifold and no difference.

Any pointers?

[NickCW]

Have you tried the MAF sensor?
Usually if you unplug it the ECU will revert to a baseline of settings, if the problem goes away when unplugged that can prove its the sensor at fault.

I know it does this on the MK1, presume MK2 is the same. Common failing on both though..