Negative long term fuel trims

[EdMay]

Hi all, I've got a 2017 Yukon with 5.3, 80k miles.
I'm having a constant problem with the engine loosing power, light throttle, it's very subtle and can also be felt during shifts. I was a GM tech for 25 years (got out in 2011) so I've got a very good understanding of almost everything automotive. I've got an HP tuner scanner and see that long term fuel trims are consistently -6 to -12 in all the blocks on the graph. From my experience, I am convinced the engine is running lean. I also see occasional random misfires but no codes.
***SO, with negative trims and a lean feeling engine, I'm thinking the PCM is FALSELY commanding lean.
BUT WHY? I very recently replaced both pre cat 02 sensors on a suspicion that they were skewed/reporting a false rich condition. There was an improvement, trims in the -4/-5 range, but are starting to creep up to-6/-7 and starting to feel like usual leaning out. I have heard that the high pressure fuel pump could leak and contaminate the crank case with gas and the fumes can migrate into the combustion process through the PCV system causing this problem but I'm not sure about this.
Running Shell regular. Cam and lifters done at 53k due to bad lobe, 4 cylinder eco mode electronically deleted, all 8 injectors at 63k, carbon cleaned off backs of intake valves/walnut blasted at 60k and catch can installed, NGK Ruthenium plugs installed at 45k, new ignition wires at 50k, K&N air filter.
I know this is a long post, but, yoou kinda need all the information.
Any ideas??? Thanks for reading.

 

[Burban22]

@EdMay

Start with the simple things:
Check your air intake, rubber boots, and plastic hose for any cracks allowing a vacuum leak. Check around intake for vacuum leaks.

are your catalytic converters good? I’d suggest replacing the downstream sensors as well.

When did this problem start after which parts were replaced? maybe connected to that repair.

Where were the namebrand parts like NGK spark plugs bought? If eBay or Amazon they are most likely knock offs as the fakes are getting very good as far as copying the packaging and even the markings on the spark plugs but you end up getting a Chinese knock off that causes misfires only last 10,000 miles.

Have you cleaned your mass airflow sensor? Is it reading correctly on your scan tool? Do you have a aftermarket cold air intake with a filter that needs to be oiled? This can kill a mass air sensor due to over oiling the filter.

If you smell the oil dipstick, does it smell like fuel if you have a failing high pressure fuel pump the smell like fuel and your oil will increase due to fuel contamination.