ls vtec problem with injectors

hey I am having a problem with my injectors. The car starts and all and it is missing injector pulls. Sometimes it will hit the injoctor pulls and run fine but only for a min, and then it will miss the injector pulls and then it will hit again. I though it was the ecu and tried a different one and it still did the same thing with the other ecu’s. Do you think it could be the wiring? If so what do I need to change? let me know guys becaues I don’t have a clue what it is.
thanks
steve