i would use a non chlorinated cleaner, just spray it lightly on the injector, and on the inside of the injector holder with it off the truck.
there is a small screen it might be on the vapor inlet tube where the hose comes from the vaporizor in to the injector holder,it is held in place with a small clip take it out and clean it good as well,if its an older truck it maybe on the top of the injector holder just to the left of the injector under a small cover held in place with two small screws. Be careful as this screen is very fine mesh and can tear/rip easily. then you'll have to replace it,it is about the size of a nickel(diameter)