Q: throuttle body on 1990 Ford F-350

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My gas mileage on my f-350 super0duty is poor. I purchased the truck after it had sat for a year.Could the throutle body need to be replaced znd would the throutle body affert gas mileage drasticlly?
(1) Answer
After sitting for a year...well...who knows. I would suggest it could need cleaned, but i'm not sure about needing replaced. You probably should check for any vacuum leaks - such leaks could cause an issue with the way the MAP sensor is reading, as well as cause the engine to ask for more fuel. Any brittle rubber hoses could have fractured causing a vacuum leak. Also, intake manifold or throttle body gaskets could also leak air. That's where I would start looking.

Other than that, realize that you're dealing with an old school 460 cubic inch monster of an engine that is very very thirsty just by design. I would expect maybe 10-12 MPG depending on what you use it for. Don't forget that in 1990, gasoline was maybe...$1.00 a gallon? Maybe even lower.