2002 taurus 24 valve OHC Duratech engine, upon stoping idles fine for 5 to 8 seconds or so then idle drops off and runs badly then dies,and sometimes does not want to start right back up without turning the key off then restarting.Also engine stumbles or flutters at highway speeds upon acceleration.Fuel economy has fallen off by about 35 % or so.Whats the problem ?

 

engine warning light on? it could be a whole host of things, bad sensor,plugs,converter going bad, filters, etc. How long has been happening? water in fuel,just to name a few. How many miles on the car? the more info you can provide,the better direction those in the know can point you.