Sublime diagnostic moment.
 

Changed the trans fluid on the GC, drove it around for ten mins, then the cruise control malfunction and 4wd service lights came on. Engine went into limp mode and wouldnt rev past 2K. Then 20 mins later a low boost code came on. ...What was the problem?

You did a shitty job of changing the trans fluid (lots of options here), hence the cascade of failures that followed.

How's dat?

ERR! False, I did a spectacular job changing the trans fluid.

Was a harness not plugged in after service was performed?

No, but close.

Neg batt terminal was corroded. Replaced it, all the problems went away. Attachment 809

Never forget to check the easy stuff before you dive into it.