I would first try to get some sea foam and run it through the engine, and gas tank. It helps to clean the carbon from the engine. Do a search on here for it and you'll see a lot of posts about it, or on www.turbobricks.com . I know it will help your mpg/ and clear up any hesitation it may have. It's a lot cheaper than swapping parts, especially if you're not sure of the problematic component, and it does your engine good. Their website is here: www.seafoamsales.com They have a listing of all the stores that sell their product.