Replacing parts that may not be bad is not a good way to save money! That said; Toyota fuel injectors are pretty bullet proof; they rarely go bad. New injectors? Out of the question! Having existing ones tested is also expensive. The FSM has directions for bench testing (volume and leakage).

 

I doubt the injector is actually bad, but it could have varnish or other dirt affecting its perfomance. I'm not saying this is actually your problem, because the truck's not in front of me to diagnose.

One option instead of replacement is to have them sent out for cleaning and balancing. I don't have first-hand experience with this company, but have heard from others that were happy with their work -> http://www.witchhunter.com/