I took my Volvo to an import specialist for a tune-up because I was having trouble starting the car after running it for long periods. They told the car's spark plugs, rotors, air filter and cables are all fine. They told me that I had some bad gas and to let the problem run it course. Well, it been two cycles of gas and two weeks now and I wondering if the diagnosis was correct? Is there some sort of gas sensor which needs to be replaced?