I'm having the exact same issue with my
MPGuino, and it's gotten worse over the last 2 months. It's pre-built, as-is from dcb. At first it would just randomly reset to 0.0 maybe once or every other tank, then last two tanks its been more often. This tank its done it constantly below half tank, and I started noticing the small black box (regulator?) on the back left-hand side (viewed from rear) was getting real hot. The other day the display finally went screwy and I unplugged it and haven't used it since. Note also the weather here just finally warmed up this last two weeks, which may be related. I followed the wiki wiring directions (an inj wire, the VSS wire, a ground under dash, and I have a +12V off the batt terminal with a 3A fuse in it like Istas has. The
MPGuino is mounted to a face-plate on the column, the rear is completely exposed so trapping heat shouldn't be an issue
Have either of you fixed the overheating problem by adding a regulator to the +12V feed?