What are the special procedures to restore the fuel injectors? on 1999 GMC Savana 3500

Do you have instructions for replacing fuel injectors?

Asked by for the 1999 GMC Savana 3500
2 answers 2 comments
first of all why do you need to replace the injectors
what is the van doing that you suspect injectors?
did tune up and changed maf censor
do u have any eng codes?