Fluctuating RPMs while driving?

An engine misfire will cause this issue as well as a throttle bore that needs service, if you have not installed new spark plugs and wires, I would do that first. I have also seen ignition coils go out as well, but I would definitely do the tune up first. Also, do you have a check engine light on? if so, please follow this guide:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is another guide to help as well:

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

and of course, please read before attempting.

https://www.2carpros.com/articles/throttle-actuator-service
and
https://youtu.be/N2nC4V9DrdQ?si=_f5NSb5lIfgCcB_Z

You won't need to reset the throttle body if you leave the wires connected.

The recommended spark plugs are typically iridium spark plugs,
ACDELCO 41168 (GM Original Equipment; Iridium)

Here is how the job is done on your vehicle and specs as well. Check out the images (below). Please let us know what happens.

Also, when the engine is idling does it sound okay, no ticking? I have seen the cylinder deactivation system take out lifters due to the lack of oiling. Even though there is no check engine light you still may have a code pending, so we should run the codes anyway.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please go over this guide and get back to us.

That could be a clue, what did it say about the emissions system? In the meantime, lets remove the EVAP system purge solenoid valve to see if you can blow through it, if so, the valve is bad and causing the engine to ingest fuel vapors which can cause the problem you are having, here is the location of the valve so you can check it out. Check out the images (below). Let us know how it goes.

The valve is probably okay, we will need the code number to see if it is a circuit high, low or open code.

You could have a leaky fuel injector or one for the cylinder activation lifters is going bad, when at idle can you hear a slight ticking sound? It might be worth it to do a compression test and at the same time we can inspect the spark plugs for discoloration.

https://www.2carpros.com/articles/how-to-test-engine-compression

The codes should help us let me know when you can supply them. Have a good holiday season. Please go over this guide and get back to us.

I have seen a MAF sensor hot wire get dirty and cause this kind of problem without showing a code. Unfortunately, there is no way to test the sensor except to compare it to a new sensor which is why the dealership mechanics have one in their toolbox just for this reason. Here is the sensor location so you can check it out. Also please make sure there are no leaks between the sensor and the throttle body. Also, do you have any exhaust leaks? Check out the images (below). Let us know how it goes.

How was it checked? Did you use a scanner to see the grams per second flow rate and how it compared to a new sensor? Like I say cleaning will not help it once it is too far gone. If you get it from Amazon, you can send it back if it doesn't help.