I Replaced Fuel Injector 3 And 4 And Spark Plugs And Cables And Pistons 3 And 4 Are Dead. I Unplug The Injector And Cables Abd Only 1 And 2 Have An Effect But When I Unplug 3 Or 4 The Engine Acts The Same. The Pistons Is Getting Gas, Air And Spark. Why Is 3 And 4 Dead????????????????