Computer wasn’t ready, you can’t rush them, just drive a couple of drive cycles as advised.
Happy it passed inspection !

 

I'm thrilled it passed. I had the car in a repair shop a few weeks ago and the owner said he noticed the CEL and wanted me to come back to fix it. He said it would need a new vent solenoid, a new vapor line and the new pigtail. I'm sure it would've cost at least $300.00 but with the help I got here I got it fixed for only $31.00. Thanks for all the help. It is appreciated.

 

As I always say, keep it clean and drive it often!

 

Glad you got it fixed so cheap, I tried all suggestions here and after 2 months of P0170 TL codes I gave in and took it to the Chevy Dealership. $1100.00 later finally past inspection after they had it two weeks. They put a valve cover gasket on (never leaked anything on me) and replace both O2 sensors with the very same ones I did.
I'm not really sure they told me the hole truth, but at least for now its ok.

 

Could have been something as simple as loose air tube between filter and TB. Some things get fixed on accident.

 

Yes, your are correct, but I checked out or replaced everything listed as possible causes multiple times before giving up. Even had two very good reliable mechanics spend all day with it and they failed each time. Now its been 3 weeks without any problems, but I would still like to know what it was.