a 525cfm 4bbl carb seems a bit big for a pretty much stock 250...did it bog in the low end? how did it run...did u re-jet it at all? take a reading of the plugs (color and condition check)and let us know what color the plugs are...the spark plugs are your first source of tuning to know whether your running to rich or too lean. Its possible that youve aquired a vacuum leak in that time, but not too likely. i cant see a stock setup 4bbl carb running well on the engine without a re-jetting, but u said it ran fine for 2 weeks. i think a good place to start would be the color and condition of the spark plugs. then u can take a spray bottle or even a propane torch (from what I've heard...although i would stick to the spray bottle) and spray down various parts of the engine and carb where a vacuum leak could be possible and if the engine changes idle speed when u spray a certain spot then its a vaccum leak that u have to fix. also..how does it run at idle..just as crappy? or is it just in gear?
