My range rover V8 will fire up first time every time. It will rev to about 3000 when it firsts starts up and then it slowly goes down. It will drop beneath 1000rpm and then less and less again. Sometimes it will loose all power and cut out. Normal driving is fine, its just when sitting at idle.

Would love any advice on what this could be as it seems a simple thing.

Any help much appreciated.

Is it a hotwire system or flapper?

Have you tried changing the CTS (coolant temp sensor) very cheap and the cause of many probs like this.

Also check for any cracks or tiny holes in the air pipes as "free" air getting in may cause a prob.