to determine if it is ur injectors, disconnect each injector, one at a time while the car is running.....if u disconnect it and it make no difference its prboably that injector/s. Try wiggling the connector wires.
Then find out if they are getting any power with a multimeter.
Did you change o rings???? If all is well then move onto ur coils and sparks.
I had a similar problem on a sr20det where the injectors where taken out and put back in the with the same o rings, the used o rings where not providing a good seal and causing it to run like shit. These are side feed not top like the rb20s.