I have a 2001 Focus SE 2.0L SPI. A few months ago I had my fuel pump replaced under ford recall 03n01, http://www.autosafety.org/Focus03N01.pdf, and then just a few wekks ago I started having idle problems. First it was just at start up and seldomly at stops. Now it is at startup, worse at stops when it is in gear, a bit better in neutral, and has even stalled twice while in park this morning. I have been searching the internet and comparing what I know about these darn focus's. I truely suspected a vacumn hose leak, but thought maybe the Mass Air Flow Sensor, Oxygen Sensor, Idle Air Control Valve, or even the spark plugs. So I went first with the easiest and cheapest first. When I started the car I could hear a slight hissing noise coming from the backside of the engine near the throttle body. Good sign. Ends up the vacumn hose that runs from the vavle cover (the cover that has the oil cap on it) to back behind the engine and under the throttle body, into the manifold, had a worn and ruptured rubber "elbow" where it connects to the manifold. I am going to replace it in about an hour. I'll let you know how it goes. 99% sure it is the problem.

Answered by jfornelli
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Okay so I just spent $10.40 plus tax for the connector, took two minutes to pull off the old one and three minutes to reinstall the new one. Drove all the way home from the dealership with NO more idle problems.
HALLELUJAH!!!!!!!!!!!!!!!!!!!!!!!! A cheap fix!!!!!!!!!!!!
Ford part number for the one on my engine, 2.0L SPI, was YS4Z-6414-BA
Good Luck. Hope this was of some help to you.

Answered by jfornelli
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