tbb2

When I first purchased the used van I was astounded that it would get 15 mpg on a hwy drive and 13 mpg around town.

I haven't done a long hwy trip for years and maybe that's the problem.
I'm now down to 8+mpg around town.

The mileage has been dropping slowly over the last 6 years. From 13 to 11 to 10 to 9 and now 8.

I switched to a detergent gasoline several tanks back to no effect. I did this after checking on recommended fuels.
I do not see anything on the scheduled maintenance that is outstanding.

Any suggestions?
Could a sensor have gotten fouled with non-detergent gas?
Do I need to load up on fuel injection cleaner and take the van out on the hwy for an hour?
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2003 Chevrolet Express 3500 Cargo Van; LQ4 6.0L V8

canucklehead

Air filters need to be changed far more often than the book says. Once a year. Its worth it. Also, I had a dragging rear disc pad, and worn front wheel bearings. Drove on them till they made noise. After changing them my mileage improved 1 mpg.
If none of those things help. Perhaps a tune up at a shop with a full size scanner. Big shop scanners sometimes find things the hand held ones miss.
How many miles on the engine? Are you using high mileage oil?
Post your findings. We all need help on this situation.
Good luck.