So I just got the same codes on my 2004 Eddie Bauer 5.4 4wd that has 225,000 on it. We got the p0128 code and the p0171 code a few weeks ago and my husband changed out the thermostat and the check engine light didn't go out so I had it cleared. It came back on today and I had it scanned again and it gave the p0171 and p0174 codes today. It is running just fine, just has the check engine light on. I read through the stuff above and I am wondering what are the simplest things to start with to try. My husband is going to be unavailable to work on it for the next two weeks so I have to drive it every day. Any ideas?