It's not the computer...

Your numbers sound pretty close to being right for an idle.

What do you think it could be?? I gotta get this thing runnin rite

Unfortunately its extremely difficult to diagnose a vehicle over the internet with the information given... White smoke is raw fuel. It could be you were free revving it on cold cylinders. It could be a few glow plugs out. It could be a few injectors aren't doing their job...

I don't know what you mean by it backfires kinda... So i have no clue there...

More information is needed or the truck needs to be seen by someone who knows what they are looking at..