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Rough Idle


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Yes 5.4L , Check engine light is on (code spits out something about fuel pressure and to check the gas cap). I haven't really noticed it more when it's hot or cold. Idles rough about 80% of the time. Every once in a while it'll idle really nice crazy

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I think I would check the codes again. My first thought is since its winter vacuum leaks are more common. If you see a p0171 or P0174 than I would for sure suspect a vacuum leak, plenum gaskets are fairly common.

The other possibility is a dirty MAF sensor.

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Does the 04 have a fuel pump driver module? I'm feeling a little to lazy at the moment to look it up. If it has one it is located above the spare tire, on the left/driver side of the truck. The aluminum housing breaks exposing the circutry inside and causes a similar complaint. Or a C.N.S. ( crank no start)

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The new style 04 has one(non Heritage), and it isnt above the spare tire until 05. The 04 has it mounted on the LR frame rail, and it is actually more common to go bad then the later ones, that are above the spare tire.

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My first thought is since its winter vacuum leaks are more common. If you see a p0171 or P0174 than I would for sure suspect a vacuum leak.

DING DING DING!

It turned out to be a vaccuum hose leak on the backside of the intake manifold

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