I have a turbo'd 8 that's tuned using a cobb. It was sitting for a week with the battery disconnected. After finally getting it started, I took it down the street, it briefly went into limp mode, then died.

Being a total n00b when it comes to this particular subject, do I need to re-flash or go through any sort of re-learning process?

 

no, limp mode is a separate issue

 

Your issues may be due to your ECU being reset and it may need a couple of drive cycles for it to run correctly.