E38 PE and Cat Protection Truck question

Bought an 08 Silverado 2500 6.0 liter LY6. Just learning the E38 stuff as all my other junk is E40 based. Please keep in mind this truck is bone stock, right down to the air filter.
A couple of notes. Started logging VE Wide band data. Truck is 10% rich at idle and very low load. At high RPM high load this thing is 20% lean, enough so that I was a bit worried and quit trying to log high load sections.
So NOT wanting to reshape my virtual VE table just yet I logged some more data on a 400 mile road trip towing a 6000 lb. trailer, obviously with the ECM back in closed loop.
PE on most trucks doesn't come in until 87% throttle, which is really about 99% of pedal travel. So I'm thinking...How can one tow this heavy a trailer at almost full throttle running stoichic and not hurt the engine? Every time I hit a hill the wide band showed a richer mixture down to almost 11.5/1 at one point, very rich. I would say too rich for a NA application. But when I looked at the log power enrichment only came into play one time...when the pedal was on the metal! ANY high load fueling done was with Catalyst Protection enabled, which was a complete eye-opener for me.
Does GM use Cat Protection to control high load fueling over PE? I don't think I have the right to question their (GM's) authority but what am I missing? If the VE table is that far off,...What are THEY missing?
One more note. 8 miles per gallon loaded and 14.5 empty. NEVER any knock retard even with cheap gas.
Engine surges and runs like crap while in open loop, warming up for maybe 1 minute every cold start. Dealer found a TSB and regapped the plugs which did not help a thing. THEY installed Tis2 latest calibration, yet when I read the tune it was IDENTICAL to what was already loaded. Also service manager claims the surging is quite normal. Looks like I'll try to fix this myself.

Discuss? Thanks for your time, John

Does this truck have a FSCM controlling the fuel pump? Do you have a way to measure fuel pressure and confirm that the ECM's desired pressure matches the actual rail pressure under all operating conditions?

No it does not. B1404 is set to fixed speed as per stock calibration.

I guess the idea with my post is to pose a question to you all as a group that cat protection must play a large role in open loop strategy? Or is GM just using this these tables instead of P.E. because they can?

Kind of still wondering, thought more guys would chime in.

John

John, I havent done anything with the E38s but Ive heard that all truck cals are setup this way. Personally Id like to turn cat overtemp protection off and use PE tables as they're probably much better to work with, but we all know how bass ackwards GM can be sometimes.

Erik,

I agree but who am I to question one of the largest automakers?

Me, with little education, trying to second guess them? No way.

Is their stock still below 3 bucks?

Like I said before I wonder if it's just so much redundancy in the ECM tables?

And how do they come up with the calculated temp anyway? O2 voltage?

Food for thought. Methinks we could learn volumes from a GM engineer. I would listen all the way.

Right or wrong there has to be a reason.

Until then I'll play till I burn it up!!!

John