The lambda cost around 100 euro and took 5 min to chance. Very easy!
I buy from a Swedish site, so I don't think it help you if a link it (Of course you can by it from a Chevrolet-dealer I guess.)

I have think about the EGR-valve, if that could cause the problem? If I have time I will try to clean it.

About the consumption, I drive on different roads from 70 to 120 km/h.

As you describe, frenzke68, some kind of power loss, when the code occurs, and no traction for me to.

Yes we try to solve this together