2008 Silverado 1500 4.8 205,000 miles and runs good.
Keep having issues with check engine light. P0121 throttle position sensor, P1133, P1153, (both upstream oxygen sensors) Heated Oxygen Sensor (HO2S) Insufficient Switching Bank??
Took to repair shop and they changed both upstream oxygen sensors and cleared the codes. Drove 130 miles, then the P0121 Throttle Sensor code came on.
Returned to shop and they changed the Throttle Valve assembly. Drove for 112 miles and oxygen sensor codes back on.
The repair shop said they're too busy to check and see what might be causing the problem....of course it's time to find another repair shop that's willing to take the time and find the issues.

I'm at the point where I might need to take it to the dealer and pay them to find out what's going on. Trying to get an annual inspection sticker but can't with the check engine light on.
Any ideas what might be causing the issues?
Thanks