Send them out to someone who has the equipment to proper assess them and, if necessary, take them apart and rebuild them and balance them.
If ALH injectors are removed from an engine, and left to "dry out", they will be bad. They need to be stored immersed in fuel or kerosene or thin motor oil or something.
I've had to deal with this multiple times over the years... the first time I was trying to diagnose a VERY low power problem on an engine that a local dealer replaced after a different local dealer tooefed a timing belt job and mashed the valves. While the first dealer had the head off, the injectors just sat on a bench (two weeks). Then they got the engine back together, and struggled to get it running at all, finally got it running but it had low power. The owner got disgusted with them (they said "it's normal, it's only 90hp!") and took it to the second dealer. They somehow, no idea how, said the engine was no good, and replaced the whole thing. Injectors sat out again on a bench, for another two weeks. They got it back together and running, and it still had no power.
Then it got to me. Car seriously struggled to move. It maybe made 50hp at best. I checked a bunch of things, found an odd deal with the motor oil: it was clean. Like, WAY clean, like it was just poured in. This engine under normal circumstances would turn the oil black fairly quickly. That was my clue: the engine was being severely UNDERfueled. The ALH has no feedback for fuel injected post-combustion. It only knows how much the QA moves in the pump, and that the lift sensor in #3 injector is generating a signal. That's it.
I sent the injectors out, they were all barely flowing. They took them apart, cleaned the solidified gunk out of them, reset and recalibrated and balanced them, I got them back and installed and bled the system.... engine fired right up, a test drive of about 100 feet confirmed the car was fixed, and the oil was already nice jet black as usual.
I have now known what to look for if the injectors have been sitting, and I have fixed many basket cases over the years following by doing just that. And now I know to store the injectors properly if an engine will be apart for any length of time.