My father-in-law (a pseudo-mechanic) did a quick "tune up" on it when we bought it, but like you suspect I think a lot more could be done. I will try the quick fixes first (injector cleaner), and then may work my way under the hood if I need to.KA24Tech said:The air flow meter is probably not the issue. I would ensure the regular tune up parts are all good with a new Nissan air and fuel filter, cap and rotor, and NGK spark plugs. Check the throttle body condition on the inside by opening the throttle plate all the way to see how dirty the inside is. I think the air bleed and idle air control solenoid may be dirty. The good concentrated fuel injector cleaners, like 44K from BG, can make a big difference after runing it through with a tank of premium fuel.