I am working on my brother in laws 99 K1500 5.3 auto 279000 kms. It was running terrible, loses power, back fires, jerks etc.... The computer tossed a couple codes that said it was the O2 sensors so I replaced them yesterday. Right away it was having the same problems but then I let it sit a run and then it started working great. So I puta few miles on it last night even tried towing and it was good. This morning working good again, then it started having the same problem sputter, back fire etc.... Computer again says O2 sensor but only one this time. If I pull over and rev the **** out of it it seems to clear up so I can keep going. Any ideas what it could be?????

spark plugs, air filter, front o2 sensors, egr valve replaced very recently

 

This must be the slow season for responses. No one replied to my question about sliding rear window on the 2008.

To stay on topic, I guess, a trip to Mr. Goodwrench.

Fuel pump? Fuel injector? Spark plug wires? Bad chip?

 

I would check for a stopped up catalytic converter.

 

The 2008 does have a sliding rear window(electric). I answered this in another post. I have a 2007.5 NBS and it has it.

 

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