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I have a 98 taurus that dies at idle ,i can keep it going by giving it gas but soon as i let of it dies. It also idles real fast at low speeds it will go 30 mph without giving it gas . wierd . dont know were to start can anyone help please.
 

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Have you cleaned your idle air control valve? Sounds like you have some gunk in there. It doesn't cost anything to pull the two bolts that hold it on and look for carbon deposits inside.
 

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that sounds like its worth a try ,does the the book that in the car show were it is located .(owners manual) or do i need to buy a chilton manual. Thanks for the help. To be a mechanic you have to stay at a holiday inn express. LOL:)
 

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Check for codes and it sounds like a vacuum leak.Check the pcv system for compromised hoses.
 

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Sounds like you have two problems. The first is the idle air control solenoid and the second may be a faulty TSP sensor. The sensor may "ratchet" at times when you change throttle setting, whereby it tells the pcm a new baseline idle setting, and the iac is commanded open. Maybe there's a little more to it than that. How can it command the iac open if it doesn't work. Ok, I'm thinking here..................Does it have the no idle cold and then start to work after it starts and runs for a bit?
 

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Or, have you had the battery out recently, then when you put it back in, was it hard to start so you gave it a little gas? IF that is the case, disconnect the battery for 10-15 min. re-hook and start without touching the gas pedal. This will reset the throttle position sensor.
 

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Maytag is right, that will reset the tp sensor, but it also resets every time you turn the key off, leave it off for 10 seconds and turn it back on. The pcm looks at the tp sensor when you pass thru on to the start position to get a base reading on what it should consider idle. Part throttle is anything over 1.2 volts, when the base line is .7 or higher. If the tp sensor ratchets during operation, that is, goes below the .7 reading, then a new baseline idle voltage is set, and a new part throttle is detemined by the pcm. This will cause the pcm to advance timing and fuel drop, causing a higher than normal idle speed.
 

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what about plugs, O2 sensors, air filter? small maintenance things can add up fast...
 

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jonzo,
Plugs or O2 sensors would not account for a high idle, and the MAF senosr would account for the diminished airflow through a clogged air filter.
 
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