tank fall off?

 

mmm, might i suggest playing around with the superchips and imputting the correct tire sizes and axle ratios, if you have modified these it will read incorrectly because it is all read off of the body control module which talks to the ecu, but i would suspect that you would have speedometer issues as well as shifting issues... worth a look, also ditch the lowes kit it might sound cool but you probably just also helped your poor gas mileage, the vaf/ maf if misplaced will in fact dump more fuel in even if at part throttle then needed because the air volume/velocity is more fierce if taken away from the factory "sweet spot". this also indicates a little light on the dash that is amber in color and says "check engine". if your set up has not been proved by an engineer it is a set up for fail.. merely suggestions

 

if you have an iPhone or iPod touch theres a great app called roadtrip that is awesome for calculating your average fuel economy, try that out. I've been using it since december and I always enter info every fillup to see what i'm getting