Ive been searching the site for ideas on how to improve the MPG's of my Xped. She has 113G miles and I dont think the plugs have been changed. The original owner said that he had 3 C.O.P. units crack(?) and had a miss fire so he had the stealership replace them but I doubt they changed the plugs. So M.C. plugs are the way to go?

I read that changing the O2 sensor at 65G will help the mpgs and Im sure I could replace the air filter. Whats this I keep reading about a MAF spacer?
Is there an ECM module that reprograms for mileage?
Thanks for the help guys.

By the way, the anti lock brake light came on the other night and then just went off. I checked the fluid but it was fine. I had just done some heavy braking on the freeway, I dont know if that brought it on, but it went away on its own. Is this just an Xped quirk?