Brianibew

Are you sure it’s not an alignment issue? To me, it kind of sounds like the toe of one or both wheels are not correct, causing it to “jump” when turning because both tires are not in sync.

Sounds like a torque converter issue, unfortunately.

Sounds like a torque converter issue due to the shudder at a low throttle input. You may want to stop by an auto parts store to read the other codes that have generated. Always an option to call GM and ask what how they want to handle the situation, as in keep driving or tow it.

There is a heater in the def tank. It may have failed.

Just my opinion, but look at the large sidewall of the tires on your Suburban and compare them to the tiny sidewall on your new Denali. The sidewall plays a huge role in soaking up those road surface inequalities. I don’t really understand why anyone would want over an 18” rim on a truck, and that is pushing the comfort limit at 18”…but I know, the larger wheels “look better”…for some reason.

Not to be a smart a$$, but maybe try a new transmission shop. Sounds like this guy is over his head.

Vapor lock is not an issue with modern fuel injected vehicles. With any luck, your no start issue will become more prevalent and you will able to recreate the issue for your dealer, or it will finally throw a code.

Sell it to Carvana or Carmax and be done with it.

I would guess if it’s not enough demand to issue a downshift, the shudder you’re feeling is the torque converter. Lots to read on GMs torque converters.

Check the wiring harness that plugs into the PS rack itself. I bet it’s not fully seated.

Put the OEM exhaust back on and bring it in.

Battery issue?

Take a video of it next time it won’t start. Call the dealer and request a tow. Show the dealer the video. Tell them you will pick it up when it is fixed. Contact GM and open up a case on the issue.

I’ve had both 1/2 and 3/4 ton Chevys and I will say I prefer the C channel frame of the Tundra in terms of ride quality. It absorbs poor road conditions much better in my opinion. I agree about the outdated tech also, but on the other hand, it’s tried and true proven tech that has been incrementally improved upon over and over instead of changing the entire design every 3 years like most other manufacturers are doing and sacrificing long term reliability in the process.

Can’t argue with you on that, lol....runs like a champ tho.