Bad COP?

[sidekicker]

I drove sport over to repair shop today. It ran smooth going into town. Turned it off when I got to the repair shop. When I started it back up for mechanic it was idling rough. He diagnosed it was a bad injector on #3 cylinder. We ordered a new injector from rock. When I drove back home, sport was running good again. Question: I put some lucas injector cleaner in gas a couple of days ago, is it possible that the lucas cleaner may have cleared the injector or is that not possible? Just wondering if maybe the injector was just clogged or dirty. Any how I'll keep driving it a little bit and see how it does while were waiting for parts.
Thanks
sidekicker