My S70 gets great gas mileage and appears to be well sorted. The engine accelerates smoothly and idles fine everyday. I went away last week and the car sat for 7 days. When I came back and tried to start it, it was a little rough for a few seconds. I gave it some gas (enough to raise idle to 2000rpm) and it cleared up after about 5 seconds. Everything is back to normal now and every morning I start up, it is smooth. Is this rough idle I experienced normal if the car sits for a week or does it indicate a potential problem?