I have 96 blazer 4.3. which has been loaned out to a family member for abt 3mos.I found out that the tank has been topped off every time at fill up not just to the nearest dollar but at least an addtl buck as well. The truck threw a p0440 code for evap issues and a day later po102 for maf sensor. Could these be related due to excessive topping off of the tank. Gas mileage sucks and the truck smells like it is running very rich. Could topping off at every fill up soak the evap canister causing the codes.Cleared the codes every day for abt a week until i had a chance to work on it but they returned right away. Took off maf sensor,cleaned it and cleared the po102 code and it has not come back as yet.Also cleared the evap code at the same time and so far that code has not returned. Could the excessive topping off damaged any componets of the evap system that i should be concerned abt.I know miles per tank is not a correct gauge for figuring mpg,but the miles per tank have been dropping considerably from around 225 to 175 so something is not right.Complete tune up was done approx 6 mos ago and a new cat a month ago. New fuel pump (gm) and spider assembly abt 2 yrs ago.No visible leaks and the truck runs pretty smooth, just drinking alot of gas and running rich.Any ideas...sorry for the long post its been a vry long day.