79 dollars would be there diagnostic charge , which if you do the repairs they would just charge you for the repair cost only. as far as a tune up you should not need actual spark plugs yet i think they are plat (60k) possibly iridium (100k) you have alot of miles left for them. but you will be coming up for a 30k service. ive worked in the service dept at toyota and honda for 13years. it is a good service to do. a well maintained car will run great for years to come.