There are many things that can be done. I will tell you what I would do for my car and you can research what you will do. First, I'd put in a couple bottles of injector cleaner and some BP, Shell or other gas that is rated with good cleaners in it to see if that takes care of it after running a complete tank. Then if it is no better, I'd pull the injectors and clean them followed by bench testing how they are working. Replace any that are bad and use new O-rings. There are plenty of YouTube videos out there on how to do that.