to test the injectors, let the truck warmup, after if starts to run badly, start pulling injector harnesses off, you should feel, see some diffrence in the way the truck runs. if one dosent respond the way the others do, bad injector. there is always the posibility that the pcm could be bad. the bad thing is that there is no way to test this. you just have to go through and test everything else, and if everything is sending the right signals to the pcm, but it is not responding properly, it is bad