Hi carfixer007,
I plan to visit a GM dealership. I suspect the P0442 issue can be fixed by use of GM proprietary tools (aka Tech 2) or PCM firmware upgrade.
I will post an update in the future.

Hi Tech II,

As I stated in my 'P0442 Issue update' I believe I found the source of the leak. It was a bad 'purge valve' that would not hold vacuum. There could be
something else, but the 'Firestone' shop I went to did not find a system issue. My future visit to a GM facility will be revealing. I suspect possible
faulty firmware in the PCM. I have looked for GM 'Tech Bulletin' releases for my vehicle, but I have found none regarding PCM firmware updates.
It is possible GM releases minor updates that do not warrant a full bulletin release. I will post an update in the future.

I cannot speak for the methodology of the 'Firestone' repair shop I visited. I can only assume they use professional grade diagnostic techniques. They
had smoked my cars evap system twice. The first time, they may have used less scrutiny. The second time they were dealing with a 'call back'. You
would think they were paying closer attention to the diagnostic testing.

I would call the place that did the smoke test and ask if they use nitrogen as well. If not, just call local repair facilities and find one that does use nitrogen. It'll be less than a dealer. Most smoke machines have a port where you can use nitrogen to charge the system. Nitrogen is less dense than the atmosphere and much less than smoke and it will find it'* way through the smallest leaks. cost You may have a leaky canister where it'* sealed.

When I take my car to the GM dealership I assume they are going to charge me for a smoke test in order to investigate my P0442 issue. I will ask them if they use nitrogen for their testing. Thanks
for the tip carfixer.

Another Avenue:

I included an attached copy of the 'I-M System Set Procedure' (also known as the 'Drive Cycle') for making the vehicle run the monitors in my post. Assuming the source of the evap leak has been found. Maybe the 'Evap Monitor' needs to run. I made two attempts of the 'Drive Cycle'. I tried to faithfully follow the steps, but I could never be sure I did something that invalidated the 'Drive Cycle'. My research tells me the 'Evap
Monitor' is the most difficult monitor to make the PCM execute. My ODB tester does not provide me with any information with regard to results of the the 'Drive Cycle':
- Did all the monitors run (or not run)
- Was any particular monitor aborted due to some invalid action (i.e. Did the driver not maintain a speed of 55 MPH for the required period of time)

Would any 'Drive Cycle' experts please chime in

My 'Firestone' repair shop seemed confident that their 'Tech 2' (or equivalent device they had) could reset all DTC'*. And my ODB tester confirmed it. I believe all my 'continuous' monitors reset shortly after I left the repair shop.
My 'non-continuous' monitors (HO2, EGR, etc.) did complete after I drove 80 miles. The only hold out was the evap monitor.