how do you know?????injectors

[jensenrcng]

to start off my truck runs ok when crusing. but when i get on the go pedal it seems to studder and i can hear the exhaust studder until the boost hits 25psi then it smooths out. i have a new ficm,fuel pump,no egr system, sct livewire(performance can tune),4"turbo back straight pipe,afe intake. so my question is how do you know when injectors are starting to go,what do they do?