I have much better software then Dinan and one of my focused area's was to make sure that fuel economy was not compromised while under part throttle load and still have better/smoother acceleration in all conditions
However if you are pushing the gas and doing many WOT pulls you can forget the fuel economy on any tune
It is also possible your O2 sensors are getting slow and this will cause economy problems of course
check your battery conditions and charging voltage off the alternator
Also check your spark plugs for excessive carbon build up
Have the dealer reset the emissions adaption routine for the DME
best of luck!