[V8] Do bad/dirty sensors always throw codes?

[Karl Middlebrooks]

On V8 #2, my starting point was a car that got 10mpg, was as loud as a Harley, little power on acceleration, and it just feels like the engine is missing.

After working on the exhaust (replaced clogged cats and rusty exhaust pipe), swapping out the FPR, and disconnecting the OXS, among other things, the car now gets 14.3mpg in town and has more power, but it's still not right. Still lopes a little and feels like it's missing on acceleration, though appears to run smoothly once up to speed.

Only code I've ever gotten is 2341. After disconnecting the OXS, I get 2342 (which sounds like what I should expect with the OXS disconnected).

Other folks with similar performance problems have replaced/cleaned the MAF and coolant temp sensors, according to the archives. However, I'm not getting codes for either of these. Is it possible that the sensors are contributing to the problem, but not enough to result in a code?