Just an update, the new air filter has given me three and 4 miles more a gallon already!! I never knew it was that important! Now the trick is, I am not yet back to my old mileage, so there still must be something going on but at least I am only a mile or two off per gallon, That is more acceptable.
If the Air Filter was so black, do you all think that there is something else in the intake systems that I can check or clean to help keep the mileage moving in the right direction?
You are going to have to get all the plugs out. You cannot look at a few of them and assume all of them are good. Each one has to be checked, and I think you are going to find one that is not that nice brown color. As far as codes go, if a plug misfires enough times, it will set a code.
If the black is on the outside of the air filter element, that would indicate a lot of blowby and/or the pcv valve is not working. That would be because someone did not do regular oil changes, so a couple of oil changes close together would be in order here, as well as a new pcv valve. You also need to replace the filter element for the supply air to the engine crankcase. That looks like a cotton ball stuck in a tube in the bottom of the air cleaner just outside the element. Some air cleaners do not have this as the supply tube is inboard of the element and is not needed.
If the engine has variable cam timing, you may need the 5w30 oil for it to work properly. BTW, if there really was a lot of carbon build up, which I doubt, but if there was, then its possible that the top end cleaning only did a partial job, and that would be worse than not having it done. You could try using a gas additive like Chevron Techron or Barryman’s B-12 or Seafoam in your gas tank to see if it helps. It might take two cans in two tankfuls of gas to finish the job.