Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
It sounds like you have a bad injector or wiring problem. Use a voltmeter or LED testlight next time problem happens to verify wiring to coil and injector is working the same on #3 as the other cylinders if not repair/replace whatever wire is different if its the same replace the injector. You could also swap the injector with another cylinder to see if misfire moves if so it will verify the problem. Let me know if you have questions, thanks.