This is definitely going to be a TLDR, but I wanted to provide as much detail as possible, I have an 08 SS auto, just over 60500 miles. Has the GM upgrade, map sensors etc.
To date (in the 2.5 yeas ive owned it) the only problems i have had is the radiator fan controller going bad, which i swapped out after getting advice here. Other than that i have had the occasional 101 MAF error which cleared after using MAF cleaner.

Was away late June and July and the car was parked in the Garage for 6 weeks. (no issues at the time)

I return from my trip and fire it up. Car runs fine the first day or two and i schedule my state inspection. Of course this is when the check engine light comes on.
P0299 Turbocharger (TC)/supercharger (SC) - low boost
P0101 Mass air flow (MAF) sensor/volume air flow (VAF) sensor - range/performance problem
P0106 Manifold absolute pressure (MAP) error.
P0010 Camshaft Position (CMP) actuator, intake left front bank 1 circuit malfunction

Parked the car and it sat for a few days. I ordered a MAF sensor just because i have had that code several times now and just figured i would swap. Also ordered a PCV which will be here Friday because i read that that could cause issues. Also checked plug connections for both upper and lower MAP sensors to make sure they were tight.
Put in the new MAF today and fired the car up. Immediately P0010, P0101 and P0106 are gone. Just the P0299 remained.

Drove the car 3 miles to the store, and it ran strong and had more boost and pickup than it had for a while. Was hoping the other would clear, but no.....

Started the car again and immediately the chime starts going off. Service traction control, power steering warnings etc. Car in full limp mode. I scan again and now have a laundry list of codes.
U0073 Control module - data bus Off
P0299 Turbocharger (TC)/supercharger (SC) - low boost
P0101 Mass air flow (MAF) sensor/volume air flow (VAF) sensor - range/performance problem
P2544 Torque management request, input signal A - malfunction
U2143 Lost communications with Steering Control (SAS) System
U2107 Engine control module (ECM)/multifunction
U2105 Engine control module (ECM)/CAN
U2106 CAN data bus, TCM - no communication
U2100 CAN-BUS Communication Malfunction

Any ideas, suggestions, recommendations?
Not sure where to begin... Can a bad replacement MAF cause these extra codes?

 

some kind of mysticism
usually in such cases they write: "first check the battery charge and grounding."

 

I concur with checking the battery charge and grounding. Also check the battery posts for corrosion.

I'm going way out on a limb here, but since it was parked for six weeks, could there possibly be some rodent damage? Just a thought.

 

Definitely no rodents (had that before when something decided the eat the hood insulator of my ATS)
Will definitely pull apart the rear of the car in a couple hours and see if there is something going on with the battery.
Thanks for the quick responses!

 

Fuses! Wires!
That many U codes indicates power to modules problems.
MAF codes usually stem from a bad connection.

 

Check the fuse box under the hood, tighten those 4 bolts, real tight!
what is the static voltage of the battery?

 

Battery post for the ground was definitely loose. So much so that i am not sure how the car was even starting.
started the car up after tightening and it was a much smoother start. Have to wait a little bit before putting it out on the road to see what clears.

 

Check the wires and plug first, but P0010 is almost always an open or short on the solenoid coil of the VVT intake solenoid valve. Don't bother replacing the exhaust solenoid valve; solenoids do not have very predictable lives, so replacing "in pairs" does not apply in this case.

Try cleaning the old MAF sensor and putting it back.

Did you disconnect the batteey for your work? Maybe your work knocked some wires around, but the new problems are likely just a battery problem, connections or age. How old is it?

Do you have 3bar MAP sensors or the originals? Either way, degraded connections cause trouble, with the upgrades in particular.

 

I tried that and got a P0013 on the first start. Luckily I was in the store parking lot.

 

Do your upgraded TMAP sensors have the plug and play connectors, or are they spliced/ crimped?