Occasional rough idle

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FORDSNUT

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Been a Ford nut all my life. Just happened to be in the previous generation so I can't guess on this. I am at the point in life where I do a lot of real slow looking in the new neighborhoods going up. At times I have to pull in a driveway or circle to turn around. Some time when I come to stop, before shifting to reverse, he motor runs real rough. This past week the engine actually stalled and when I restarted it acted like the battery was weak. But when it caught battery showed good and has not acted up since. If I shift to neutral and raise the rpm it clears up. In the old days it would be the carb loading up. Never sets mil and once it straightens up it runs fine. 08 5.4 with 175k miles. Any input ? Shooting it is not an option. Thanks
 

99WhiteC5Coupe

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Been a Ford nut all my life. Just happened to be in the previous generation so I can't guess on this. I am at the point in life where I do a lot of real slow looking in the new neighborhoods going up. At times I have to pull in a driveway or circle to turn around. Some time when I come to stop, before shifting to reverse, he motor runs real rough. This past week the engine actually stalled and when I restarted it acted like the battery was weak. But when it caught battery showed good and has not acted up since. If I shift to neutral and raise the rpm it clears up. In the old days it would be the carb loading up. Never sets mil and once it straightens up it runs fine. 08 5.4 with 175k miles. Any input ? Shooting it is not an option. Thanks



Clean the inside of the throttle body bore - it is probably dirty (including the butterfly valve), which does not permit enough air to flow at idle (when you stop in gear). That causes a rough idle.

You also may have a battery that is beginning to fail, or loose or corroded battery terminal connectors and battery posts. Removed and clean the connectors and the terminals with a battery terminal cleaning tool.
 
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FORDSNUT

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Thank you for the reply. Hood up tomorrow. If you promise not to laugh I'll tell you my first guess. As an old guy (78) I jumped at the thought it had to be a timing issue which quickly led to chain/phaser fears. I did dismiss that because it is so erratic. thanks again.
 

99WhiteC5Coupe

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Thank you for the reply. Hood up tomorrow. If you promise not to laugh I'll tell you my first guess. As an old guy (78) I jumped at the thought it had to be a timing issue which quickly led to chain/phaser fears. I did dismiss that because it is so erratic. thanks again.


Let us know what you find. No laughing here.

Working on my vehicles and those of my family for years taught me to check the simple (and often easiest) things first.

You may want to also check the air intake connections (clamps secure and tight), and the duct for any splits or cracks.
 
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