Stop in for a cup of coffee

Hey frank how can you tell if one fuel injector isn't performing fully? 5,9 motor. Have a slight miss on the R/T and cant figure it out.
Unplug injector one at a time. Thats where a noid light comes in,plug light and start it. You can use a light bulb as well. If all cyls flash and you can identify which cylinder doesent change then you have identified which cyl is misfiring.