Going with a custom chip allows you greater flexibility with better programs, IMO, than going with a programmer. And if you're thinking about upgrading injectors, the programmers simply don't work well, from what I am told, with modified injectors. Not first hand experience, but hands down input from my customers is there's nothing like a custom chip.
As for injectors, the only way to tell for sure if they are modified is to open them up for inspection. A less accurate way is to add a high hp chip and if it smokes quite a bit when you get on it, the injectors are most likely modded. If there's a little more smoke, then probably not. 'Course the problem with that is everyone has a different opinion of what a lot of smoke is.
These older trucks need to be woken up. Big air filter, 3" down pipe with a straight 4" exhaust, Pyro & Boost gauges (trans temp gauge if you have an auto), Stage-1 injectors, and a good custom chip really make for a nice, powerful, all around fun truck.
Chip: You can contact Jody at DP-Tuner, they are a sponsor here listed up in the Sponsor forums.
Injectors: I can help you there.
As for the other stuff, you got me, I'm not into bling stuff... But check up in the Sponsors Forum here first, and ask more questions.