I tried to find something about this in a thread and maybe didn't use the correct search phrase. Anyway, please bear with me.
I have recently added a Kury air filter and iridium spark plugs to my engine. Then I added Torque Loops and V&H Monster mufflers. I'm happy with the changes but I don't feel like the computer has adjusted to the changes very well. I get a bit of backfiring when I decelerate and my gas mileage has dropped from a pretty steady 33mpg to 28-30 mpg. Is it possible I may have a busted O2sensor or something? I'm not very mechanically minded but it seems like these changes should have helped my gas mileage, not hurt it. I did gain a very noticeable amount of power with the changes but I don't want to damage my engine.
Has anybody got any ideas on what, if anything, I can do about this? To me, the small backfires are embarrassing as I consider it an indication of an ill-tuned engine.