1993 Ford Taurus will not idle half the time
 

I have a 1993 taurus with a 3.8 six cyl and it has had an idling issue. sometimes it idles but 70 percent of the time it sputters out. i have been told the car is too old for a cpu diagnostic so i am wondering what can be done to fix this issue and how badly my fuel economy is being effected by this.