I know there is a million threads about p0171 and p0174 so let me say I’m sorry to add to them. I have a 97 f150 with a 4.6, its high mileage and been worked hard so I don’t expect anything amazing but its got problems. Since I bought it 3 years ago it has been showing p0171. P0174 is a newer development. It thinks it has a lean fuel mixture so it is dumping gas into the intake to the point where you smell unburnt fuel in the truck. I have identified and fixed several vacuum leaks and replaced the MAF, EGR valve, VMV, injectors, and some other stuff, all of which was actually bad. As well, performance has been getting worse. Now, it lacks low end power to such an extent that I need to use a lot of clutch to get it moving, and once its in gear, it will not make any power until the rpms get pretty high. I don’t know if the performance is even related to te codes. I am running out of ideas and wanted to see if anyone has some thoughts. Also, most of the PCV hoses were missing when I bought the truck. I can’t seem to find a diagram of where they actually need to go, so if anyone has a diagram/picture of the pcv system I could use that. Thanks for any help or suggestions.

Lou