2002 cr125 wont run right

I just bought a 2002 cr125. the bike runs with a couple carb problems i believe. I live in CT and wonder if some of it is due to the cold weather right now. It idles fine, but then sometimes stalls once coming to a stop directly after riding. Also, it wants to stall when i start off. I know its not like my street bike, but it shouldn't need to be reved that high when starting off. Finally, when you get on the throttle from just cruising slowly it stutters for a second like bogs down before it goes. The bike has aftermarket reeds, a 410 main in 3rd position. Any ideas of what to do? Thanks

thanks for the ideas, I had tested the bike when it was still fairly cold and it seemed fine. I tuned the air screw to richen it a bit and it seems to be better. I also cleaned the air filter and it appeared as if the previous owner really over-oiled it, (i'm not sure if that could've been a partial factor.)