2000 F150 4wd 5.4l Ok, so I've had a rough idle when the truck was cold since October. when it would warm up, it would go away. I also had P0174 & P0171(system too lean bank 1 & bank 2) After reading up on the forums, I replaced a few deteriorated vacuum lines, then the usual culprits, IAC, EGR, MAF, TPS, IAT, the list is LONG! But nothin worked! Then I sprayed carb cleaner along the vacuum lines and manifold, then ran a fog test, nothin again! Finally after talking to a local shop I learned that the intake manifold gaskets were the problem on some he had worked on, even though they wouldn't show up on fog or carb cleaner test. So yesterday I picked up the gaskets, and tore into her!




Been drivin her around tonight and I think it's finally fixed(true test will be tomorrow morning) I was scared to dig into the motor that far, but to be honest, it really wasn't as hard as I thought. I definitely recommend changing the plugs and cleaning the throttle body when doing this, and be sure to get the tool to remove the fuel rails. Hopefully this helps some of you find that pesky idle problem, and if anyone wants more details on this feel free to PM me or reply.

 

let me know how it goes my 4.6 is doing the same thing

 

Turns out that was it! Started her up this mornin, about 22 degrees F, and she was as smooth as could be! I know my 97 with the 4.6l was a lot different than this 2000 with the 5.4l, the 97-98's look a LOT easier to dig into.