Hard starting

I have the GLi6 model. When I start it up for work of after work lately, it will idle for a few seconds and shut down by itself. With a mixture of turning the ignition and very short idles it just does not want to idle for like two to four minutes or so. When it does come to idle I will let it warm up and drive off. Depending on what ever is wrong, the car will drive smoothly as always and just shut off, having me swinging on the ignition again. There has been times like this afternoon where I can hear it losing power, and immediately regaining power again without me touching the ignition or stepping on the gas. It mostly happens when my car is cold. She is well looked after, getting regular services and is in great condition otherwise.