New Owner and need help

[Mediamonkey11]

Definitely sounds like an engine issue, I test drove one that drove perfect for a bit then did the same thing, I could tell it was from the engine though, was a definite miss. Even if the PO did that work I'd check the plugs and coils w/boots out thoroughly.

 

[own1bigtruck]

Well add the DPFE, and EGR vaccume pressure regulator to the list...still doing it.....

 

[mjlcobra]

FWIW I have a brand new DPFE sensor from AutoZone ( duralast ) that I tried to solve the P0401 with. Ended up having blocked EGR ports on my intake. If the coils, cops, and plugs have been changed, I suppose I'd go with fuel filter and air filters. They're cheap enough and probably need changed anyways.

 

[1stGeExpedition]

Check all of the plastic plugs for your coil packs. If one is not properly connected or a wire is bare it can cause your symptoms. It'll miss (may or may not throw codes) and stumble. Kinda sounds like a plugged cat or exhaust leak too.

By checking the cop connectors I mean physically. Disconnect them one at a time and inspect each one along w/ the wires.

Do you have codes related to this? I read that you said no codes to pull but did you scan it?

Maybe your PO disabled the SEL like mine did. Does your service engine light illuminate on the dash when you put the ignition to on before starting?

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[1stGeExpedition]

I changed my cops not too long ago and didn't fully plug in the #7 connector and it stumbled and ran like crap just like you describe.

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[own1bigtruck]

I replaced all of the COP's and plugs again last night. She runs much better now! The stutter is gone and she idles nice now! Still have a small exhaust leak where the down pipe connects and a squealing idler pulley but I feel much better about this investment now. I guess now its time to order all of the suspension components and start rebuilding the bottom end....

 

[jlo82585]

the 5.4l is notorious for an exhaust leak on the R side exh. manifold. Its a ford design flaw of using non-stainless steel and poor exhaust heat dissipation. Usually a real pain to fix, mine has the same issue, the manifold bolts are either missing or are so rusted they don't even resemble bolts. I had a shop quote me $300 to fix the leak alone so i'm saving up...