So I changer out my ECU chip with a Bavauto chip and now I notice that my mpg gauge (which is just a vacuum gauge) kinda bouncing up and down at steady throttle. I have checked for vacuum leaks but none found. Any ideas...?

my mpg gauge (which is just a vacuum gauge)

Really? Seems like it would have something to do with math, but what do I know. I'm sure it gets some info from the DME :dunno

Fueling inconsistencies due to injector or MAF changes?

Rob

*Edit* Does the behavior still exist if you uninstall the programming?

The MPG gauge is driven by the ECU... As far as I know. While it might not be much more than a glorified vacuum gauge, it does have something more to do with the fueling calculations the computer is making.

Mine stopped bouncing around when I replaced my ailing oxygen sensors.