gauges glitching? battery issues, please help.
I recently been getting a dead/weak battery issue, obviously its just the battery, not the alternator, had the battery tested, it holds a charge for a while, but tends to weaken after 2-3 days. I have another issue possibly related, not sure. My gauges seem to be acting funny. My average mpg says 27.2, but when I filled the tank up, the miles to empty said something weird like 330. when the miles to empty readout would say something like 435 before today 27.2 times 16 gallons is way more than 330. I went into engineering mode and the average mpg said something ridiculous like 20.9 mpg, which is funny, because last time I went into engineering mode the fuel mileage said something like 29.7 mpg. Is it possible that my fuel mileage suddenly dropped, or I'm leaking fuel, or is something glitching? I'm checking for leaks, so far nothing. no check engine lights, no DTC's.