i have a low mileage lesabre(under 20,000) that won't start. it cranks, i hear the fuel pump run when i turn the key on, but all i get is maybe a poof like it's trying to start. the car sat for years, but since i started driving it i have replace fuel pump, fuel filter, fuel pressure regulator. and cleaned the gas tank. it seems like it may be the fuel pressure regulator. i have changed it twice and that fixed it last time. would something make it go bad or is there something else i should be looking at?