Re: Do spark plugs go bad if a car was parked for a long time?
You didnt say how may tanks of gas you've put through it since you tried driving it and/or when you did start it, if the gas in the tank was not drained and refilled. My assumption was that it wasnt and had gone bad, plugging up your injectors, etc.
Go buy a good injector cleaner and run that through a tank or two of gas. If you dont see things start to improve you may need to get things cleaned out by a shop.
Spark plugs shouldnt be a problem. They can sit for years and not go "bad". If you can pull the plugs, they may give you an indication (check the color, etc) about whats going wrong in your engine and why your MPG is so bad.