Fuel trim adjustments aren't made that abruptly. As well, the ECU will go into open loop mode climbing that grade........which means O2 input is ignored. Besides, the smoke would've been black were it from fuel.

PVC and/or valve seals might explain the oil burning. The smoke could be condensation, but I wonder......does your truck have the PAIR reed system intact? Well, a while back, for some reason, my wife's 3vze had water in the resonating chamber and was being sucked into the intake. The hose from the PAIR reed valve had water in it. I still have no idea why that happened, but it hasn't happened again since. Needless to say, it's something you might check. Might also explain the code.

 

Just throwing this in there, I too had water in my resonator chamber (I first noticed a damp air filter and in AZ this just doesn't happened, traced it to PAIR reed). 2 weeks later a blown head gasket. I'm thinking water coming through the reed valve was the first signs of moisture in my exhaust. Keep your eyes on coolant level.

Was the smell sweet? Kinda like burnt sugar? That's your old friend glycol talking

 

No blown gasket here. That event was well over a year or two ago. No problems since. Alteast, not with a head gasket.