Throttle body mod. (http://www.ramforumz.com/showthread.php?t=46431
Check to see if you have a plenum leak. If you see oil when you look inside the throttle body, then you have a blown plenum gasket that's robbing you of power. If you fix it, get the Hughes Engine repair kit (http://www.hughesengines.com/Index/p...3&partid=26190
) and do the Kegger mod (http://www.ramforumz.com/showthread.php?t=80192
) while you have everything opened up. The plenum is a known problem on these trucks. If you wanted, you could get a different intake manifold that might get you some better power and eliminate the plenum design completely, but from what I've seen on dyno charts, the stock keg style manifold is best for low end power (but can be improved by doing the kegger mod).
Other than that, any cold air intake when added to your exhaust should be a good idea too. Personally, I am going to do the throttle body, kegger, 1.7 Harland Sharp rockers, and an SCT tuner from Hemifever on my 5.9. I don't know if the rockers is a good choice for you if you plan on doing a cam later, nor do I know what ratio to go with on a 5.2 since the valve lift height is different for your engine.
I wouldn't do the tuner until the end because you'll want Hemifever to modify the tune every time you add stuff to the engine. Better to just get everything done and then add the tuner last to make it all work together better.