2017 Tahoe with very rough idle

[dksharp]

sounds like you just need a better diagnostic, like a misfire graph and/or compression test that would probably tell you a little more
the fact that the mechanic says to "trade it in" means either it's something they could probably fix easily and flip it or they don't even want to deal with it.
injectors on some of these trucks have a extended warranty period under special coverage which you could check at the dealer with your vin.
in any case you are on the hook for diagnostic cost. It could be beneficial to invest in a decent scanner, for this scenario and any future ones.

These are some good things to go after. A compression test could tell me alot. Especially if I have a stuck lifter. I also plan on shooting the motor with a temperature gun while idling to check for any temperature issues.

 

[vcode]

Does the vibration go away if you increase rpm's at idle by 100-150? A lot of these trucks have a rough idle from GM setting the idle speed so low.
Probably not your issue if it just started.....

 

[houstontaylor]

I did have vacuum leaks on my 2003 Tahoe with 355,000 miles causing a rough idle. The latest incident turned out to be an old loose vacuum hose from the brake booster that looked okay at first glance. However, when I pulled on the hose I could see that the connection at the engine was loose, so I replaced the hose and replaced the clamp at the engine with a stronger one for the new thicker hose. I have done the same test on the air intake duct another time and found the connection to be loose and leaking air where it attaches to the throttle body. And I did also at one time replace the pcv hose that was worn and loose at the valve cover.