Gasoline changes in the past 15 years

I own a 93 dodge dakota. it runs very well, and has 226,000 miles on it with all original parts except trans. right off, i understand that the engine has quite a few miles on it, but there is no oil consumption or other problems existing. all the emmissions systems are working fine. my question is this, I used to get about 17 mpg with the truck when it was new up until i had about 150,000 miles on it. then one fall, six or seven years ago, my mileage fell to about 11 or 12. it hasn't changed since then. i was wondering thta if about that time if the gasoline mix was changed at the pumps. is there more ethenol in it now than there was in 1993, and when did these changes take place? i keep a log book of all repairs and gasoline i use in the truck, so i know exactly when the change occured. also, it wasn't a slow change, it happened basically overnight. i am trying to find answers to why it changed, and i am also trying to find ways to increase the mileage again. i'm hoping that with some minor electronics changes, i could improve the overall mileage. any help would be appreciated!

Also, I forgot to tell you that it is a 5.2l (318) V-8 engine, auto tran, and 4wd
Thank You!

Asked Dec 23, 2009
Edited Dec 23, 2009

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