2000 Passat Wagon - MPG display problem
 

I have a 2000 Passat Wagon V6. Whenever I start my car and start going, the computer reports the average mpg as going up, and then it gets caught in a loop for a while at 15. For example, it'll read 15.0, 15.2, 15.6, 15.8, 15.9, 15.0, 15.2, 15.4, etc. It also happens when the mpg is decreasing, so it'll go 15.2, 15.0, 15.9, 15.7. This is irritating, as it's sometimes caught in the loop for up to 5 minutes. Has anyone else had this problem, or know of anyway way to resolve it short of having the computer replaced?