Need help diagnosing sputtering/misfire

[2 Sweet]

Buddy of mine has an 02 Tundra 4x4 with the 4.7 V8 (not the VVT, the older one). It has headers, stock cats, no mufflers, but the rest of the truck is all stock. The truck runs great in all conditions (cold/hot, idle, accelerating, etc) EXCEPT when you romp on the gas. Basically anything more than half throttle, it bogs and cuts out bad and doesn't gain speed.

 

We hooked it up to a scanner, it's throwing lean bank codes for the rear o2 sensors. Replaced those and it's still doing it. MAF is clean, catalytic converters look good. Where should we look next? Fuel filter? Ignition coil? It only acts up under heavy throttle, so it probably wouldn't be fuel related, would it?

[Green Bastard]

I wouldn't rule out fuel related, WOT is when the engine is going to demand the most fuel. Fuel filter is not a bad place to start, at least if it is not the problem it's cheap.

[Farkas]

Fuel Filter, Plugs, Ignition coil

[93 RX-7]

Since it's giving lean code, I would look at fuel system. Check fuel pressure.

[Rocky31186]

Fuel filter, seen it a ton of times at toyota. Not saying he is an idiot, but I really don't get why people do not do regular maintenance..

[2 Sweet]

Yep, fuel filter was the culprit. Sometimes it's the simple shit that gets overlooked. The truck runs perfect now