When you say "stuck" do you mean open, as in "leaking" or is it not spraying? Flooding the cylinder or a misfire due to no fuel in that cylinder? I'm not sure the ecm can cause a particular injector not to fire. It's my understanding that the cylinder is triggered by the distributor and module. The ecm just tells how much fuel to allow the injectors to provide, based on temp and air flow (or vacuum, in the case of earlier speed density systems). It can turn on/off the ground that allows the injectors to fire, but if the other injectors are firing ok, then the pulse signal is making it through the ecm. Someone correct me if I'm wrong. I'm getting really rusty on efi since I only own carbed Fords now lol!
You should be able to hear and/or feel the "click" from each injector when it's running. Keep in mind, a wet plug could be caused by no fire, as well. I'm sure you've tested plugs and wires already, but I figured it was worth mentioning.