I sent a ? earlier with the wrong year ... i changed four o2 censors and now the car is running very rough and is back fireing on at least one cylinder It will not idle ..
2003 Ford Taurus on 2003 Ford Taurus
If it was an O2 sensor code that was stored initially make sure the part number of the parts you fitted are correct and the right sensors are in the right positions. Is there a Check Engine Light on now, if so scan to determine which codes are now present. Check to see that vacuum hoses or electrical connectors were not inadvertently knocked off during sensor replacement.