2003 having issues with codes from hell p0174 p0171, new maf, air filter, checked for vacuum leaks, runs normal, codes keep coming back and I clear them, 2 or 3 hrs later back on!!! Help making me nuts

 

What engine do you have ? Some have known trouble spots.

Bad PCV valve, Bad check valve on brake booster, Bad gasket between upper and lower intake.

 

4.0 2003 ford sportrac

 

[QUOTE=TBG1550;2191561]4.0 2003 ford sportrac[ thank you

 

OBD2 TroubleCodes p0171 & p0174 on the 2001~2003 SportTrac V6~4.0L~SOHC Engine commonly indicates a leak in the 5/8"ID PCV VacLine between
the PCV Valve on the rear of the left driverside ValveCover & the PCV HeatExchanger on the right side of the IntakeManifold throat.
Those rubber hose elbows are notorious for cracking+leaking after 10+ years of service.
If your PCV line is factory original, I'd just replace the entire RubberHose+PlasticTube "L" assembly with 5/8"ID HeaterHose,
& replace the PCV Valve itself if it's more than 2years old; at least clean it.
Click here for more info on the PCV for the Ford V6~4.0L~SOHC Engine.

PCV Hose Assembly Ford# kcv190 & PCV Valve Ford# ev268