if your commute is mostly highway, that efan isnt going to do much. Your fan doesn't run much if at all when you are moving at highway speeds. You might squeeze a tiny bit with the efan and a tiny bit with the tuner, but honestly your best bet is to keep it tuned, use synthetic oil, make sure your egr and o2's are newish, sparkplugs are good, run some seafoam or marvel mystery oil to clean out the sludge. Do all that and you will be running in peak form. Between a tuner (~300 to 350), efan (~300 if you buy a kit), and other stuff you might buy such as a cai and exhaust system, you could spend 1500 bucks trying to increase power/fuel economy, but that will take forever to get back the money in the incremental ( likely ~1 to 2mpg) gains.
But, if you have some extra liquid cash and want to save a few bucks monthly and have a more fun and powerful truck, there are certainly some options.