Poor cold tick over-RR Classic 3.5EFI

Rangerover V8 3.5 EFI 1987. Auto

Starts fine and runs great…………except when cold.
It’s had new plugs and leads, new ignition module to the side of the dizzy , a new (second hand) extra air valve. and BOTH temp sensors
She’ll start fine but until she warms up properly, if you DARE put her in drive too soon, the engine seems to choke itself to death and stalls where upon it will NOT start unless the air pipe is taken off the extra air valve at the front of the engine. If I take the pipe off, (on the outgoing side of the valve)she’ll fire up OK and the revs race like hell until the pipe is plugged back on and she settles down to a VERY lumpy tickover untill properly warmed up and then she’ll tick over as sweet as a nut.
I thought it was the extra air valve at fault but replacing it hasn’t helped.

Any ideas please?

Most likely faulty AFM. Could be ECU aswell, but I'd put my money on the AFM.

The engine gets unmetered air when you disconnect the hose (more air than AFM is telling). Hence the AFM gives faulty information OR the ECU reacts to it's information incorrectly giving too much fuel.

You can check the AFM with a multimeter according to the workshop manual. It's basically a potentiometer. Easy to do. Or you can try with another unit(s). You should also check for air leaks in the system while you are at it.

Thanks TimoV, much appreciated.