I have a 140 with dual side draft carbs. I seem to be having carb problems. I rebuilt both carbs and just cant get the thing to run right. It is incredibly hard to start and then I have to keep the rpms up by pumping the throttle until the engine temp comes up. Once I get on step it runs great. Acts kinda funny at idle. SOmetimes idles low and then after running on step the idle is hi. Any suggestions?

I am thinking about converting to a single carb but the price for the weber conversion is expensive. This is my clunker work boat and I don't want to spend a fortune on it. Has anybody converted by getting a manifold from a car? ANY ideas would be greatly appreciated. If you know some carb tuning tricks I can try I would welcome them as well!