Verified answer

I don't think the 98 Taurus is Flex Fuel meaning it can run on regular unleaded and ethanol.

You didn't experience any problems before because your motor was still burning the regular gasoline. Now that its burning ethanol its probably knocking. The motor has to be equipped to burn ethanol and your engine computer has to be able to recognize that its ethanol not regular fuel.

You probably want to drain your fuel tank and put in regular gasoline if you don't want to break something like your injectors.

If the car was not designed with the flex-fuel option, and I don't believe the 98 taurus was, you shouldn't use E-85 gas in it. Drain the gas tank and make sure you replace the fuel filter, then use regular unleaded and you shouldn't have any more problems

Yes, it will. If you do not have the special Flexfuel engine (made specifically for E-85), do NOT run the car on it. It clogs the car engine and gums up the spark plugs.

And even if your car was equipped to run E-85 you would not only pay more for the fuel but get worse mileage.

Heh, shouldn't you have asked on Yahoo! Answers before putting the E85 in the car?

After you put the right fuel back in, you may have to replace your O2 sensors as well, depending on how fouled up they got since your car was probably running rich as hell trying to make power.

ethanol should only be used in an engine that was designed for it. you can probably take care of the problem with a complete tune-up, and a flush and fill of the gas tank.