excessive spending on gasoline ..?

hello good afternoon, I have a 2007 Dodge
Ram 1500 5.7 truck, it was working perfectly
suddenly I started giving only 9 pmg in the
city, I already changed oil, spark plugs,
oxygen sensors, egr, I restarted it by removing
the battery 3 hours, but it continues  Anyway,
if the same thing happened to someone and I
solve it, I would ask him to guide me, I would
really appreciate it!  Thank you..!