why my 2002 Chevy silverado 2500hd. using lots of gas (7.5mpg)

I was 'informed' the air filter has no impact on fuel mileage, only engine performance... Your thoughts. I always thought engine performance played a role in fuel mileage.

I saw that and left it alone. Have fixed a lot of problems with filter changes, rich codes, performance, etc. Does have effect on fuel trim.

Yeah, i know all about how the computer can maintain the optimum air fuel ratio 14.7:1 or close to it but the last time i put my hand just partially over an intake plenum inlet,,be damned if the engine didn't die!! That cat has not seen a real 'farm country' restricted air filter,, evidently! Put a piece of cardboard in place of the filter and see how she runs.

I know Lol, just didn't go any further with it, Thanks for the memories.

you guys are to cool,love the engine dont need air to run,that clean filter makes all the difference in my mpg,be cool guys!

Thank you. Happy trails