AF, i think the dude meant new injectors.
MPG is a funny character. It seems no 2 trucks will get the same, even when set up similar. and careful what you "read" about what others are getting, some lie even if they don't mean to. and don't believe the guy who tells you he's getting 20 some plus with an automatic (but i AM getting 18
).
If you suspect "dirty injectors", try emptying the fuel bowl, filling with Stanadyne, and running that.