"I don't really want to take the rubber boot off and the injectors out to repeat the test."

I seem to remember lifting the plate with the boot in place, by going in from the front with a slim screwdriver. A long social finger will do it too, I believe.

You don't need much lift to simulate the idle condition.

The problem is more than likely an injector. The fuel distributor uses small valves at each injector line, but they rarely go bad. If the break pressure is different between injectors then an injector may be faulty, assuming the pump is building pressure fully. A weak main pump will show up during an injector test.
You don't mention what the injector spray pattern looks like at large flow rates. The pattern should be conical, and the injector should make a whistling or whining sound while spraying. If any injector shows an offset stream of fuel which is not well atomized a few inches from the tip, it is bad, and will not form a good pattern at the small idle opening. Even a bad injector will work at high RPM and full load without much in the way of symptoms. It is at idle that the spray pattern is critical.
Replace all of the injectors if you find one or two bad ones. A quick repair is to replace the bad ones only, but the best idle quality and engine performance comes from a new set.

Since the fuel distributor regulates flow it adjusts pressure to each injector as necessary to achieve flow equal to the other injectors. The only way an injector could stop the flow is a clog strong enough to resist full system pressure. A partially clogged injector would actually work fine at low flow rates.