I disagree, find a decent shop that has "experience"with your engine's injectors. injectors are not injectors, the world around. That may have been true years back. But now some are old school, with o-rings or retainers, without, adjustable, throwaway, some are electronic controlled others mechanical...new ones multiport, solenoid controlled, variable timing, common rail, individual, etc, etc.
Sadly, they (the shops CAN and often do) make them WORSE and you are confident that it can not "be an injector" because they just were repaired/fixed/rebuilt. After you spend $$$ on other things, then you come back to the injector, again.