codes P0174,P0171 ford F-250 super duty 5.4 L

Hello spiritwolf, hopefully this answer will help you. First of all those are two of the worst codes ford has ever had as there are many reasons why they are occuring. The first thing you need to look for is vacuum leak. The most common place is the hose comming off the pcv. It gets contaminated with oil after that is starts to get weak and developes a hole. The next thing to check is the maf sensor. It is located inside the vehicle air intake system. If you take the housing for the air filter out of the vehicle you will then be able to remove the sensor itself. Look for dirt buildup on the wires of the sensor. To clean this you need to purchase maf sensor cleaner available at any parts house.I will caution you right now do not use brake parts clnr as the solvent will ruin the sensor, you have then added an unwanted expense. If these 2 things are not the problem the next thing to check is the fuel pressure. If it is below spec check the filter first. It is funny how out of site out of mind plays a big part in fuel pressure. By this I mean that the filter is one of those things that we dont normally associate with the codes that you have. If the pressure is ok then you might check into having the pcm reflashed to cure this problem as there is a tsb about those codes without any other symptom. Hope this helps