the injectors out of the 93 engine you know were working perfectly before you took them out? How long were they sitting? dose it take the same amount of time to start the car every time, cold vs warm?
Dose it sound like its down a cylinder? pull either the spark plug wire or an injector plug and see which ones do not change your idle.
ur vac line from the fpr is connected to the intake manifold right?
everything was working fine before you did your little tune up correct? try putting things back the way they were if you dont get any ideas.