Poor gas mileage . . . 2001 Sonoma SLS 4wd 4.3 litre

I am getting VERY poor gas milage in my Sonoma. the truck runs fine, no rough idling, no hesitant exceleration, no black smoke out of the exhaust.

Connected diagnostic comp to omb (sp) and no red flags appeared!

If I read my manual correct, I have a 18.5 gal tank and maybe I can get 200-210 mpg. That equates to 11.5 mpg.

Thats worse than a V8!

Any suggestions?

I've checked the obvious, leaks, tune up . . brake stuck on!! 8^)