Have the injectors professionally serviced. Typical charges I've seen is around $30 per injector (Canadian Dollars)
You can soak them in Laquer Thinner and put them through an ultrasonic cleaner but they won't be clean. When they are done professionally the pintle filters are replaced and the injector are put in an ultrasonic cleaning machine but are also energized to exercise the injector plunger at the same time. It's a low voltage pulse feed that you can't replicate without specific electrical equipment and if you energize with 12 volts dc to the injector, you'll fry the pulsing coil in the injector.
Bottom line, Pay the pros for this work.