Car dies when idling? Gets worse the colder it gets... Any ideas?

Its a 2004 Ford Taurus with 125,000 miles. The check engine light is always on and by always I mean always. The car normally runs great, however on colder mornings it will not idle. It runs a little rough on these mornings too, a little delay after hitting the gas peddle before it'll speed up and when I stop at Stop lights for long periods I have to shift to neutral and it barely stays running. If I stay in drive it will die.

On warmer mornings now that we are getting into Spring it runs like a champ, no idle problems no delay it does not run "rough" at all. It passed emissions but they told us that Mass Air Flow Sensor needed to be replaced. We did so thinking that would solve the problem and the Check Engine Light is still on and it has made no difference in how well the car runs...

I had this issue before with a previous car in which the Fuel Filter and Cat. Converters needed replacing but that car ran very rich and would not exceed 3500 rpm's period (made highway driving difficult for a week). Neither symptom is present in the current situation.

Country Boy2014-03-16T13:19:54Z

#1. Change the fuel filter first.

#2. Go to a Ford Dealership and ask them to read the fuel pressure on the fuel rail pressure fitting. This is a very inexpensive test BUT the fuel filter must be clean to get an accurate fuel pressure reading.

#3. Ask them to read the fault code on your on-board computer. These are the only people who can read the code and give you the exact cause of which emissions part that needs to be cleaned or replaced.

Rustycorvair2014-03-16T14:22:22Z

For $25 you can get a code reader. It will give you a trouble code and you can look it up online. They usually list the most frequent causes for each code. Or go to your parts store..many of them will read the code for free

Paul2014-03-17T03:09:12Z

Sounds like an idle air control valve to me, but that would show on a code reader I believe.

Don S2014-03-16T13:04:19Z

Very likely it is the Oxygen sensors