do I have to take the complete fuel rail assembly and all that other crap off just to replace a fuel injector? I have an 89 iroc 5.0 tpi

 

There isn't much difference between replacing one, and being able to replace them all (or all 4 on that side).
If you can reach and unbolt the 4x 10mm bolts holding the fuel rail down, then maybe.

When I last changed injectors, I removed the plenum and the passenger side runner... to loosen/remove the 4 fuel rail bolts to get enough clearance to remove the injectors. Whether you disconnect the TB, or remove it from the plenum is your choice.