i plan to do a minor service at home this week... oil, filter and coolant, since its been about 6-7000km since i last did this (the odo broke so i dont know exactly

) so i was wondering if i need new plugs, leads, airfilter??? what else needs to be done every 5000, so i can make sure to do it?
EDIT : Id also like to add that my fuel economy with petrol AND gas is absolutely crap at the moment, and would like some suggestions as to what a cheap and easy fix might be. Also, the idle gets a little rough sometimes when im at the lights or something... it seems to pulse or surge or something... Also, would an ECU reset do anything for economy?