2012 4.6L sputtering/stalling while driving

Hey everyone, I'm having an issue with my 2012 4.6
I purchased the truck in October, and it has been running flawlessly until last week. Randomly, while driving immediately after starting, it cut out while under light acceleration. RPMs dropped to about 200 from 2500, the torque converter unhooked, and then it slammed back. The truck drove the rest of the trip just fine.
The next day it was way worse. Under any form of acceleration or even maintaining speed, it stalls. Sometimes it's worse than others; often the stall just feels like a jerk, and the RPM drop is barely visible. Other times RPMs drop to ~500 and then slams back. Interestingly, when I slam the gas pedal and RPMs are up in the 4000-5000 range, it happens less; not completely gone, but less.
I was in a situation where I was forced to drive the truck about 90 miles, and it stalled the entire way. I was able to maintain about 60MPH, but it stalled and jerked consistently, whether cruising through a small town at 20PMH or running 60 on a state highway. At low RPMs, the stall is very gentle, but under load and at higher RPMs its pretty rough.
It mostly idles fine but has also stalled once or twice (but never quite died)
The only code is a P2238 O2 sensor code. I bought a can of MAF cleaner and thoroughly cleaned the MAF sensor - no change. By the way, it happens at varying elevations. From 6000' to 11000'.
Any thoughts or ideas? I've searched online and not found an identical situation.
Thanks!

 

I would think that if you have a O2 sensor code, that would be were to start. Does the code have history to coincide when the problem began? This would in my opinion have a great effect on high altitude as fuel injection is a metered role with air density/air amount. Remember the throttle body supplies metered air and the fueling computer mixes fuel accordingly. With a faulty O2 sensor it may be having issues talking to the computer about mixing the air/fuel ratio properly. If you have a code that is were I would start. I may be wrong but it is just an opinion. With these sophisticated computers it would not surprise me at all.

 

May need to get the ECU flashed to the correct elevation. I bought mine in LA and had to get the ECU reflashed for altitude when I moved to Reno at 4000 elevation as with higher altitude the oxygen is less dense. May fix the issue.

 

Thanks FWDTundra, I took your advice. In my previous experience, an O2 sensor simply told you that the cat was no longer doing its job. But apparently the upstream O2 sensor measures air/spent fuel to help compensate for altitude. Therefore I replaced the offending sensor (Bank 1, Upstream), with a Delco sensor, and so far the truck is running great. In addition, I cleaned the MAF and EGR thoroughly. If issues continue I'll look into having the computer reflashed for 10K+ feet of elevation, but so far so good. Thanks everyone!

 

wllewis84
I am glad that you have it running the way it is supposed to run. It is always a relief when things go right.

 

Depending on mileage and costs, you may consider replacing all of the O2 sensors.