2008GS

I have a strange issue that occurs only when outside temp is 80 degrees or above; When I push the start button, the car fires and runs but quickly shuts off. Repeat until car finally runs. I would say this is not a starter issue but rather fuel related or CPU related. This issue did not occur at all during the winter! Possible fuel meter issue or carbon build-up that causes issue only during hot weather? Anyone else experience this issue? Ideas?