UPDATE: I've clean flashed this ROM about 4 times already and I found that my problem is that this ROM doesn't come with the Native APN editor.. therefore, In the APN screen the option to "ADD New APN" is simply not there, only the "load defaults". When I search for a network it finds AT&T but I get an error in the notification screen saying that it can't connect to this AT&T network. I really don't know how the rest of you AT&T users are getting by since I haven't seen any posts about this, and it doesn't seem like it works with AT&T right out the box like other ROMs I've flashed in the past.
FYI: temporary fix
Where I'm at right now is I downloaded an App called "BuildProp Editor" from the play store and edited the code(hit menu key and select edit) and added the following lines at the very end of the code:
ril.sales_code=LOL
ro.csc.sales_code=LOL
Once finished hit save, and restart the phone. Once the phone boots up again and you go to the APN settings the Native APN editor is back and I'm able to select "New APN" and enter the settings manually. HOWEVER, it says im on 4g but my SpeedTest only downloads at bearly 1M (I was getting around 10M before I flashed this ROM) when it ACTUALLY finishes all the way since it sometimes disconnects randomly.
I'll try different APN settings I guess and see if I have better luck, but I'm wondering.. why am I the only one having these problems? I'm starting to think I missed something even though I followed the flashing instructions by the letter. I would have given up on this ROM already but you guys did such a great job with it and I like it so much that I'm still fighting for it (the S-Pen LightSaber sounds are just sick!!

. So Please, how did the rest of you AT&T users get this to work no problem??