If you put a cold air package on it you will get a "richer" mixture and your economy will drop. You need to make sure that the manifold intake air heater is working. Replace those plug wires and drop the plug gap down to .035" or as small as you can get it with a smooth idle. If you get higher gears then you are going to reduce your milage. You are already running an overdrive that is close to 2.70 or 2.80. Replace the air filter and change your driving habits.
Most "Cold Air kits" are an oxymoron.Unless the filter is sealed from the engine compartment heat and is pulling cold air from outside the car,it does nothing to aid performance or economy.As Paul stated they just make your engine run richer,and in some instances hotter.
On the snorkle of the factory air cleaner is a foil "hose" that goes from the exhaust manifold to a vacuum operated gate mounted to the snorkle. Until the engine gets up to temperature it is supposed to pull all the air going into the carb from around the manifold to get it warm. After the engine warms up it is supposed to keep the intake air at 200F. This gives you better milage and prevents carburetor icing. It is usually the first thing that people disconnect before they begin asking how they can get better milage.
The 97 is fuel injected and uses hot water circulated Thur the throttle body to heat the incoming air.
Look at the aerodynamics of an Explorer, or most any SUV for that matter. Your pushing a big square box thru the air, not very slippery at all. That coupled with the full time 4wd is a recipe for poor gas mileage. I'm not knocking your Explorer, I had a 92 with the six and 4wd with auto locking hubs, and it only got about 18 mpg at best. It was a great vehicle, loved the room in it and the ability to pull a trailer with it, but not the best choice for gas mileage. If you need mileage, get a small car to drive, and just use the Explorer when you need it's size to haul stuff.
ya your probly right. I dont really wont to get ride of it because it run great and i need the v8 to pull my boat and my lawn trailer. So maybe ill get a small truck with a 4cylender in it to drive back and forth to work (something cheep).