2005 Colorado, I5. It seems at about the time I reached 45,000 miles, my mpg went down by 5mpg. I was getting around 25 and now I'm down to 20. I've changed my air filter and have been runnunig injector cleaner. It sure feels like I have to mash the gas pedal alot harder to get going. I did put new tires on about that time, but put the same size on. Anyone else notice such a big drop in mpg? Any other suggestions would be appreciated.