99 ford F-150 4.2 idles up and down

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Old 09-17-07, 10:37 AM
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99 ford F-150 4.2 idles up and down

Hello there, i have a question maybe somebody out there can answer. I have a 1999 Ford F-150 4.2, It runs terrific but lately when i come to a stop it idles high then comes down in a few seconds. When i am at a stop and press the accerlator it again goes up in idles and slowly goes down. any help would be appreciated. But other then that this is a great truck.

thanks'
Gary
 
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Old 09-17-07, 03:08 PM
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Check for vacuum leaks, especially around the P.C.V. lines & the area where the upper & lower intake manifolds come together. Have you tried to read codes?? Usually a code will set if it has a leak very big. Good Luck, Roger
 
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Old 04-29-08, 10:58 AM
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Originally Posted by howlin View Post
Hello there, i have a question maybe somebody out there can answer. I have a 1999 Ford F-150 4.2, It runs terrific but lately when i come to a stop it idles high then comes down in a few seconds. When i am at a stop and press the accerlator it again goes up in idles and slowly goes down. any help would be appreciated. But other then that this is a great truck.

thanks'
Gary
It sounds like one of your sensors are gone. Put it on a diognostic.
 
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