yeah the a/f guage is not going to tell you if your running rich or lean at half throttle the numbers will be so fast and inconsistant it would be pointless. like stated its mainly used for tunning at wide open throttle. you should be looking at somthing that messures load or injector duty cycle, thats mainly what fule econamy guages monitor in luxury cars.. get a scan guage i think it will tell you everything you need to know.
plus with the a/f guage your talking about (autometer a/f guage for ex..) its not going to tell you anything if your reading it off of a narrow band o2 sensor, we like to call these "light show guages". if you want a real a/f gauge (wideband) your gona have to get somthing like am AEM uego or an NGK afx wich requeires you to use a standalone o2 sensor, and they arent cheap..
2004 Silver XLT 4X4
4.0L SOHC | 4.10's Open | 5spd Automatic
3" PA Body Lift| 265/75R16 BFG A/T's | James Duff Traction Bars
K&N Air Filter | Gibson Muffler
4x4's go off-road
SUV's go to the mall