I have a 2013 Cat 700 Limited. Ran fine when out away last fall. Tried to start it this spring. Starts and idles fine. Stumbles and backfires when applying throttle. Replaced fuel line, fuel tank breather. Rubber block between throttle body and intake manifold, pulled fuel.pump and checked rubber seal on pump and cleaned sock filter with carb cleaner. Drained tank as much as I could and put 2 gallons fresh fuel in. Any other ideas? I can't find a service manual for it yet either. Tried the lawnmowerparts.com link but only found much older manuals. Thanks for any help you can offer.