Well... I've got great news. After going through all the suggestions as it relates to replacing the ECM, fuel pump, cleaning the Mass Flow Air Filter Sensor, the IPDM, and almost redoing the catalytic converter and throttle body, it turns out that my problem was a bad connector on the crankshaft sensor, which was the reason for throwing the code. As I suspected, the stealership was not going to even look at this, their fix was, well since we replaced the crankshaft sensor, the next thing the book tells us to look at is the throttle body. And so, the reality is, had I had them replace the throttle body, the problem would have remained.
So, instead of taking it back to the stealership, I trusted pretty reputable mechanic and he checked it out thoroughly and found a wire that connects to the crankshaft sensor was bad. And so, after messing with the wire on the crankshaft sensor and the crankshaft sensor itself for sometime, he was able to discover that this was the true reason why my car was dying/losing power and shutting down while driving. He called the stealership to see how much the connector part would cost to replace, and of course they told him he had to get the entire IPDM I believe. And so, with a heart to save me money, he found the part in a junk yard off another Armada, spliced it and put it on, and Praise God, I'm happy to report that my truck has been running good since then.
Having said all that, I'm glad I did go through all these things, because much of this stuff like the fuel pump and cleaning the Mass Air Flow senor needed to replaced and clean anyway. But, I want to thank everyone for your comments and the sharing of your experiences. I've learned a lot and even though I'm not a mechanic by any stretch of the imagination, I found myself doing something that I thought I'd never do. And I owe it all to you on this forum. Thanks so much!!!