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The battery died on my Ford F-150, so i replaced it. Ever since then when the truck is idling the RPMS go up and down. It used to be set at 750. It stalls out sometimes. Someone told me that you have to let the truck run for awhile so the computer can reset. So we did and its still doing it. Then I took it to a service center they could reset the computer and check for any fault. First he said it was the ac compressor and then changed his mind and said it was the alternator. So i bought and installed it. . . and nothings changed. Now i find it odd that because the battery went out that this is happening. I gave the truck an oil change/ fuel filter too. Just in case (it was past due for that too). Anyway ideas ???

Answers from the Automotive Experts

Barb Petrey, President - DBK Enterprises Inc at Jiffy Lube What you should first do is get a true diagnostic test done before you go changing any more parts. This will help isolate the problem area which may be the cars control module.

Helaine Kurot, Owner/Technician at 360 Automotive I would take it to a qualified repair shop and have the batt and charging system rechecked. There are two different options for the alt on this vehicle (output amperage rating is different). They both look exactly the same but the part number is different. It may also have a completly seperate drivability issue that coincidentaly happened at the same time, that should be diagnosed by a qualified technician.

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