Gas mileage?

I had my small pickup's engine completely cleaned, new filters, radiator flush, cleaned fuel injectors, etc. For a few weeks I did my normal routine of driving to work and was getting great mileage. Then I drove it on a 4 day trip of about 700 miles and have noticed a bit of difference in my mileage after I got home. I get about 280 miles on a full tank now. Before the trip I got about 315 miles to a full tank. What could cause this change? tire pressure (I have not checked my tires since I returned)?Gas mileage?
I am just throwing this out there. I noticed that once when i drove from florida to denver, when I got to denver I stayed for about 2 weeks. My gas milage went down as well.



This comes from a runners point of view and what i kinda know about cars so please don't chastise me if i am wrong. it kinda makes sense (if there is an elevation change) that maybe the computer compensated for a lower o2 consentration/vice versa and is now running a bit more rich because it thinks its still in the same situation.



It couldn't hurt anyway (even if I am way off) to check the pressure in your tires and to take off the battery lead and leave it off for at least 30 minutes. After doing this it will reset the computer and do self checks etc... It couldn't hurt to try it.



I have no idea if any of that would affect anything but in my mind its def. a possibility.Gas mileage?
need to know your location-california has formulated fuels that has poor volitility-arizona on the other hand has better fuel and you will get better mileage-high density cities ususally have this poorer performing fuel.Gas mileage?
could be tire p.s.i. or a change in drivers or driving condition's did you run your AC , traffic lights, hills,rain exc-exc
Try useing a better grade of fuel....sometimes the gas you get from stations like Arco don't seem to get the better mileage...try a tank of Chevron or the like