Rough idle, Error codes P0171 and P0174, Please HELP

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Aug 12, 2008 | 11:11 AM

ejkob

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Rough idle, Error codes P0171 and P0174, Please HELP

I have a 2000 explorer V6 4.0l SOHC, sport with 170K miles . Last year the check engine light came on and after a FORD inspection, was told by that the manifold gaskets were leaking. OK, I get them changed and the codes continue to appear. I have relplace both O2 sensors, the MAF, the IAC and I still get the codes. ON top of that, the engine at idle seems to search and fluctuates around 400 to 700 RPM! It sounds like a vacuum leak, but I cannot find one.... Where should I look next? Could it be a fuel problem? It runs fine outside of idle even pulling my boat? It it the DPFE or could it be the ECT. I have also replaced the computer too. Please advise as this is driving me nuts!!!

Aug 12, 2008 | 12:25 PM

87 XLT

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From: SoCal

Not sure, but I think the SOHC has the PCV valve at the rear of the engine with a hose coming in from both sides.

Have you checked for a leak in one of these hoses?