Well, LH injectors are awfully expensive and not that prone to fault. If you still suspect the injectors, look at the plugs to see if they give a clue to one or more cylinders burning poorly. Make sure all the injector solenoids are operating by listening. You can remove the electrical connector of a suspect to test for a difference in engine sound.

There's another check of injectors I used in conjunction with a fuel pressure gauge: The OBD provides a test cycling of the injectors in "mode 3". I connected one at a time (engine not running) cycling it with the OBD while watching the residual pressure drop. Goodness was indicated by roughly equal response from each injector.

I'd get LH injectors from the junk yard - that's how reliable I view them. But those injector cleaning service sites make you wonder otherwise.
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Art Benstein near Baltimore