actually when i was at the dealer we used to use a chemical that would run thru the fuel line and run the motor not using any of the gas in the tank and would clean the fuel rail and injectors thats about the best way ive seen it done besides actually physically cleaning them
Having them professionally cleaning will help, but resealing the injectors and housings will make a huge difference. They can be a huge place of compression loss and vac leaks. It made a big improvement on our 1990 4runner. I would clean and re-use the original injector housings, and just use factory seals. The china made housings don't fit nearly as good as the factory units. I threw them in the trash.
regards