To tell for sure if it's running lean you would have to have access to scanner and look at short term fuel trim to see if computer is trying to riching mixture l have seen the injector holder relief plugs clog up you could try removing the main injector the one in the center with 4 Phillips screwspull out the injector make sure the o rinon the end of the injector is good some times it takes some force to remove it after you get it out try some carbcleaner were the injector was removed there will be to small holes clean them out and use shop air after to make sure it is dry than reinstall the main injecter and see if it runs good just a thought.