Again, this sounds like an extremely rich condition. You said float & jets are stock setting? Stock jets are too rich for nearly every condition, except maybe high elev. Make double sure float isn't too high , as this will flood it. I use a fuel level gauge (much more accurate). Also make sure air filter isn't restricted (not too much oil in it) & check the condition of the reeds, making sure they are installed properly. Clean & repack silencer. I hope this helps & good luck! :D