This is TBI or MPI? If it's TBI you can check the injectors with a timing light and see if they are firing, and whether they have a good spray pattern. Code 45 will always show up when equipped with a 3 speed auto, disregard this one. My Ramcharger had EGR problems as well, probably could have been cleaned but I replaced it. That will definitely cause some bad running issues. Start with the free things, EGR can be cleaned with carb cleaner.