The injectors should fire all at once. When one pair are grounded by the ECU the other pair is grounded as well since the grounds all come together before they split to the injectors. I re-checked all of the injector wiring and am there is nothing wrong with it. What should be the voltage going to the injector plugs. Turned ign. to on position and checked voltage at the end of each injector power wire and batt ground. Got readings of 12.4v. Is that where it should be? Gonna try throwing in my new set of injectors right now. Hopefully that will solve the problem. Thank you for the replies.