Idle limp mode
 

Currently working on 2005 limited. Currently have been told by a shop through diagnostics that alternator needs to be replaced. Question is would bad alternator cause rough idle and when pedal is pressed vehicle stalls out. I have a new throttle body and alternator ready for install but before tearing into it I wanted to get some advice. New to five hundreds. Any help would be appreciated.

It is possible if the alternator is sending out bad signals that are getting into the electrical system.
To confirm this , all you need to do is unplug the alt and see if the problem stops. If it goes away , replace the alt. If not, there may be a fuel supply problem or ign syst problem. Further checks would need to be done.