Thanks for the reply, man!
Turns out the board really was a D800. The phone was running a combo of D802 software and D800 Kernel. Funny thing is, EVERY app/test/IMEI check revealed it to be a genuine D802. Whoever did this really went to some extremes to cover up the tracks. But since I updated the entire firmware including kernels, the phone softbricked.
Moosani Electronics in Saddar near Star City Mall helped me flash the stock AT&T D800 firmware and it fixed the problem!
Everything was working fine but I found out the mobile hotspot feature wasn't working for some reason. So I rooted the device and downloaded "SQLite Editor" and tweaked the tether settings. That fixed the problem!
As for the garbage AT&T bloatware, I simply uninstalled all of it.
Everything is running silky smooth now!
A word of caution for those seeking to buy a D802. Just make sure your phone has a genuine D802 board!
God Bless!