oxygen sensor?
 

My 2001 F150 when starting (especially in cold weather) runs extremely ruff until it warms up and then it does fine. I have been told it needs an oxygen sensor. Can you tell me where it is located and how to install? Is there more than one sensor I should replace?

Steve

It is extremely unlikely that an O2 sensor will cause this symptom. FWIW, there are two upstream sensors that control fuel trim, but the computer does not use them on cold starts until they come up to temp.

Any CEL? Checked for codes?

Which engine? Some have common problems.

Steve