That's pretty low to be a carbon issue, I would check for vacuum leaks first, then make sure that the choke is not hanging up. How good are you mechanically? Not a shot, just a question. If you are pretty good, you can true the "water fix"...if it IS carbon somehow, run the engine at fast idle and SLOWLY pour water down the carb...the water will break up the carbon. BUT if you pour too fast you will damage the engine, so if you are not comfortable with that, DON'T do it.