Just my 2 cents but... I had original wires for 100K miles and was using bosch platinum plugs for about 75K miles..... replaced both of them to try and increase fuel mileage - it did nothing at all.
Well, I was thinking of just getting the front 02 sensor replaced.. that should probably fix a bunch of milage problems.
Also getting a new fuel filter would hope .. I help, since this car most likely has its original filter on lol