i think im having a problem. I just bought a 1996 f250 with a 460 in it. the engine has a 650 cfm holley carb. my problem is i seem to be getting about 3-5 miles per gallon just driving around town nice and easy. the engine is compleetly stock except for the holley carb and what i think may be an RV cam. Is this just normal gas milage? or is somthing wrong. the exhaust smells rich. what should i do? i have a brand new edlebrock 750 available to me and i actualy know how to work on those, would this be a good carb for this engine?