Reduced Engine Power with codes P0120,P0220,P1516 and P2135

Hello,

I have a 2006 GMC Sierra Denali 6.0, ive been having Reduced Engine Power problems for a while, ive gone a few month without getting the alarm.

a week ago got in to start the truck had the alarm it wont clear by turning ignition off the on again, ive had the Throttle body changed, Throttle control actuator module, found the wires from throttle body were not connected well when that part of the wiring harness was replaced, changed plugs, plug wires( truck runs very poorly when in limp mode), odd but the battery has drained twice this week never happened before.

any help would be appreciated thank you