Low idle when cold. High idle when hot.

I have a problem. The car idles very low when cold. 500 ish rpm. Once the car is fully up to temp it idles high. Sounds around 12-1300 rpm. Also when warm the idle hunts. Drops down and rises back up continuously. Also the car seems to be using quite a bit of fuel 25-30 mpg.

Any help would be much appreciated.

Cheers.
 
If the 02 sensor is behaving I'd look for a vacuum leak after the MAF with a stone cold engine... I had something similar on my k11 1.0 coil pack facelift and mine was a vacuum leak. Micras are quite simple so the issues are usually also simple in nature. Car not throwing any dash lights?.. might also suggest lost sensor if that's the case
 
Yeah barely run at all disconnected.
I did the old disconnect with the MAF, you have to wait a while for it to get used to not having it before it settles down to normal idling.
It would still fall on the odd occasion for a couple of months after that, then it ran OK for the rest of the time I had the car.
 
I changed the whole throttle body with all the sensors today. Still runs exactly the same. I' going to look for a vacume leak.
 
Pretty much rulled out a vacume leak. I just unplugged the coolant temp sensor. And the hunting idle stoped. Also the fan started. I have never seen the electric fan start before. Maybe the hunting is the idle jumping between cold start and operating temp.
 
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