Mine's been on and off the for 4 cycles now ('01 3.0, 125k miles)

1st time, it was P0171 and P0174, I reset it with the ODB tool

It came back on within a week, then disappeared by itself (suspected gas cap). Then reappeared and disappeared the next week. Didn't get the chance to read codes.

Then it was on again. Re-read and it was P0171 and P0174 as before, Plus a new one P0455 (did a search and gas cap was a likely cause). I noticed my gas cap is loose, even though I make sure it clicks after I reset it. Possible wear and tear on the cap?

I've driven 2 weeks / 1000 miles since the last reset and SES hasn't lit up yet. I've also made it a habit to just click the gas cap tightly every morning until I get around to replacing it.

If it lights up again, then I'm gonna clean the MAFs and start poking around.