TBI injection mods - Throttle body spacer, a variable fuel pressure regulator, a fuel pressure gauge port to read what your fuel pressure is, and the 'extreme tbi mod'... It's an explanation how to space the injector pods higher and file down the ridges leading into the throttle body ports. The first three things are on eBay, Google the last one.
Some TBI's came with a performance ignition module below the rotor in the distributor. It's called the 369 module because of the numbers that appear on the casing. If your truck doesn't have one already, they can be found in most junkyards. it's not a huge bump in performance, but it allows the spark to advance sooner allowing the engine to produce power lower in the rpms
Beyond that I'd recommend a cam, headers, and some exhaust work. But keep in mind that most TBI's run lean from the factory. Helping it breathe better will require a boost in fuel pressure... hence the regulator and port listed above.