Hi my g40 won't idle when cold but it's fine when warm were is a good place to start looking to sort this cheers
I had this once, for me it was blue temp sensor on the way out, there is a faq somewhere to test them out with a multimeter.
Cheers will start with testing that on weekend
This written by haysey is always worth a read with electrical or engine problems:
http://www.polog40.co.uk/forum/index.php?topic=214.0
I'd also look at the ISV. Might be stuck open in the warm position.
If you need anything, i have a ISV and the blue sensor with thermostat etc for sale.