I have a 2000 Taurus SEL with 114K.. Today the car was Very low on fuel so I went to the gas station and added fuel "87" to it then I drove off.. Like 5 mins later the Emissions light or whatever it's called started blinking then it would go solid then blink then solid. Is this really bad gas or something more serious. The car rides perfect it's just that when I stop or it idles it has a little shake when the light is flashing but ok when solid.. I plan on taking to mechanic on monday though so any input may help such as should I just burn this fuel off then buy a better fuel grade next time?