sounds like a pcm problem to me. if it does end up being the pcm, dont let a mechanic charge you $600+ for one. they can be found for $200 or less online. flashed and everything. takes about 5 min to install it. this sounds real similar to when the pcm died on my old durango

 

i always check my alt by starting the truck and then removing the batt cables, if the truck dies, replace alt... not very technical but has worked evry time

 

good news I'm back up and running, we replaced the battery as it was original from 03/2005 and got a new one, took the alt with us to the auto parts store and had them check it, it passed, so it went back in the truck

thanks for the advice and help