I don't understand the fuel trim numbers yet but will read up on that next.
"Fuel trim" is discussed in the FSM, that's not bad place to start reading if you want to know more.
If you don't mind, if the fuel trim readings are off, is there a primary culprit?
I'm not strong in that area, let's see what others say.
Replacing all the O2 sensors might have been the better approach, since you were already at work on them. O2 sensors can be considered a service item, and a weak / bad O2 could push the fuel trims out of line.
But IIRC, odd fuel trim values can be caused by a number of factors, e.g., a failed injector, a vacuum leak affecting only one cylinder or bank of cylinders, a leak b/t the exhaust manifold and the head,...
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