I stumbled on this site by mistake. I was in search of purchasing O2 sensor(s) for my '97 F250. I read with interest bigdaddyt's problem with his 5.4L, and turbo ted's response.
My situation is I get the same trouble codes, but unlike bigdaddyt, I'm enjoying great engine response and better gas mileage.

This all started back in October when the "check engine" light came on. Interestingly, at the same time, my fuel gage indicator stopped working. It's stuck on "full". I now rely on the trip odometer as to when to fill up. This is how I know I'm getting better gas mileage, 14 mpg, as opposed to 12/13 mpg, same type of driving.

Turbo-ted now has put me in a dilema. He's saying the trouble codes don't indicate bad O2 sensors, whereas I read in the "Haynes" manual that they do. I was about to order and replace them when I stumbled upon this site.

I can live with broken fuel gage, but my problem is that I live in Phoenix, AZ, and a mandatory emission check is required for licensing. Ugghhh...

I've taken the vehicle to what I thought was a reputible repair facility, where they did the full blown diagnostics. Their recommendation was replace all 4 sensors, and the fuel pump module, for around $1,200.00. All things considered, I opted out. (One of the reasons being that my vehicle only has 3 sensors. What were they going to do, have a free lunch on me?)

OK, anyone have any ideas. Talk to me Turbo-ted...

 

clean the maf sensor with electrical cleaner, and reset the computer, then check for a vacume leak near the intake manifold.

 

Look for a vacumn leak. check the PVC closely, the tubing tends to crack. I replaced and clamped all vacumn lines and the lean bank code cleared up

 

When I had those codes it was a vacume leak. I replaced 1 O2 sensor myself , against the dealers recomendations, he said it usually isn't a sensor. My leak was at the brake power booster.

Good Luck, John