fuel line clean out

does any body know of a good way to clean out the fuel lines
i replaced the injectors and one went bad again
the guy i got the injectors said there could be contaminats
in the line (rust from condensation)
does any body know how to fix this
the fuel line has special fittings on the ends so i can't just
put in any old line
if any body has any suggestions
let me know

thanks