If you have a Multi-meter- a good way to check if any one of your injectors is to unplug the connector to each injector, stick two lead wires into the injector so that you can probe it, and test for resistance across it (ohms). It should read somewhere around 13 ohms if the injectors are indeed working. Another great way to test them has already been listed- testing for misfire in either the spark plugs (spark plug/dizzy/wire problem), and testing for a bad injector via unplugging while running. However these tests wont tell you that you injectors are clogged or damaged, and should be also visually inspected
Diagram to measure ohms just in case
https://i.ytimg.com/vi/wi90kx32c10/maxresdefault.jpg