Hmmmm.... very rich... if this is the .46, try using a larger prop, like an 11X6. You may just be under propping it.
Also go back, read the instructions for the engine/low speed NV, and set the carb as specified. ie If they say to adjust the high end first, then the low end, do it as prescribed. A call to the horizon Hobby Tech line will go a long way.
Here's the web address: http://horizon.hobbyshopnow.com/support/

Jetts