Driving down the interstate Saturday as I merged into traffic from the on ramp, heard a thump and the engine started shaking and had zero power, CEL came on, blinking at first. Coasted as far as I could to next exit and pulled into office building parking lot and determined truck not drivable.

It almost cuts out at idle, and sounds like a terrible misfire and shakes violently. Giving it gas has almost no response on rpm, and when I tried to move my truck, it was sluggish and cut out twice.

Since I was on the way to a wedding I left it until Sunday. I had my brother tow me to the nearest auto zone so I could have the codes pulled and get an idea of what's happening.

Guy said code P2196 (O2 Sensor Signal Biased/Stuck Rich, Bank 1, Sensor 1) and code P0174 (System Too lean, Bank 2).

Just so I'm clear, bank 1 would be passenger side? Why would I have two conflicting codes, Wouldn't the whole system run only rich, or only lean? Is it possible his scan tool couldn't detect other codes, misfire perhaps?

My exaust manifold (pass side) went out about a month ago (been looking for courage to tackle that job) but I haven't heard of people having issues with the 02 sensors clogging up. Just for background on truck history it's 2004, 5.4, 135000k miles. Plugs changed at 110k, all fluids changed at regular intervals, MAF cleaned around 115k, new fuel filter at 120k. Never had any engine issues with the truck, and no prior indication in driving until it happened.

Not sure which direction to take, be it tackle the lean problem or running rich issue.

Any advice much appreciated.