2 new fuel filters and crappy MPG, am I missing something?

[rnrn]

OK,

Ran two cans of techron over the last month on near empty belly. Went in for oil change and fuel filters (M60 takes two) and without changing driving style I am down about 2 mpg on this tank alone. I don't feel any surging or starvation--she feels the same.

Checklist to make sure I am not missing something easy here? Dirty MAF, etc? Again, as always, thanks and I'm all ears...

[Garlic Breath]

Buying the same brand gas?

[TheGeak]

o2 sensor?

[infinity5]

I vote O2 sensor! Stomp codes don't work in my car but if i ever got bad MPG that'd be the first thing i'd do regardless. Check for vaccum leaks as well, why not? check your tire pressure... hmm.. not sure.

[Russell]

I have been told that heavier oil such as 15w40 or 20w50 will lower gas mileage. Not proven to me.

[rnrn]

Same gas- usu. Shell or Mobil. Oil is 5-30 synthetic. Both O2 sensors were Oct 2002, 23K miles ago. I'm gonna clean the MAF filament with denatured alcohol and see what happens. I'm wondering if there is a build-up of oil from the K&N recently cleaned (!). Don't know why I didn't think of that one...

[rnrn]

Mileage down even more now, about 3-4 mpg lower in the city and about same on highway. Can O2 sensors go bad that soon?

[rickm]

When mine failed it went very quickly, I drove to the beach and was getting 28mpg, drove home and was getting 16. :P I wasn't even pushing it either. Can you test the sensor to see if it's bad?