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Running Lean all of a sudden...

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Started driving the truck daily a couple weeks ago with the nice weather...mods are in sig.


Went to a shopping center, came out and left, on the way home CEL comes on.


Pulled codes when I got home. PO0172 and PO0174...Fuel Banks 1 and 2 running lean...


Cleaned MAF, checked all vacuum connections (replaced a vacuum cap that was dry rotted.)


Reset codes, ran fine for a day then threw the same code again.


AFR gauge reads between 14.5 and 15.3 during cruising, bottoms out at 10.0 whenever its in boost, and at idle in Park it will read 17-18.0 or max out AFR on lean side. A blip of the throttle will pull it down, then when it settles it maxes out again. Before this issue it would always be 14.3 during cruise, and 10.9 under boost, I've never seen AFR gauge go above 15, except when engine braking...


I have read that a leaking intake gasket will cause lean conditions, but would it be all of a sudden? Motor only has 10k miles on it...highly doubt its intake gasket.


Fuel pressure gauge reads 60psi constantly, so I feel like I can rule out fuel pump.


At this point I am hoping maybe its just bad gas? I use the same station and pump religiously...truck has been problem free for over a year with the blower.


I am looking for any kind of help to remedy this, let me know what you guys think.



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