just bought an 04 f150
when i flip the info button on the guages to mpg it was at 14.6
the day i bought it friday.
its been dropping ever since, right now its at 12.9
whats the deal??

i also just changed the camshaft sensor because of rough idle
and it hasnt changed the rough idle

 

The mpg will drop if the engine is not running correctly. Your rough running condition may be what is causing the MPG drop.