05 2.2 i-ctdi idle fluctuate on cold start

Hi all have an 05 preface accord that has a rather annoying start up issue
On cold start ( car sitting overnight ) car starts perfect but seems to idle strange somewhere between 800/900 rpm
I think this is quite low for cold start maybe I'm wrong
Soon as I rev it it's fine then back to idle it does it again
Only lasts for approx 1min then idles perfect

Anyone any ideas ??

From memory that idle speeds sounds ok. Is there any missing or hesitation?

Sorry I mean on cold start revs jump between 850 rpm and 900 rpm just for the 1st min but other times it will start in the morning and idle in or around 1000rpm
Quite confused with it