Others and me posted a engine tuning part in this thread on conditions:
http://www.rcuniverse.com/rcarchive/23/2002/10/4/70780

Possibly too lean try richening up a click or two, and check for air leaks which will make the engine run lean and inconsistent as well. Possibly getting a bit hot as well due to being lean..I'd rather have an engine a bit to rich than lean when tuning..
I am familiar with drilling a hole in an OS 46 was the only one that was nessecary for me, but I later corrected the issue with the newer carb body for the OS 46..

OS 32 Air Bleed Hole (I will not reccomend doing this-Do At Your Own Risk) I do not condone this mod!

Air bleed hole in the casing. The modification provides more air at the idle for the combustion process, thus leaning the idle for proper mixture. The air bleed is positioned so it will only provide extra air to the carburetor from 0 to about 50% throttle, at that point, the throttle barrel covers the airbleed. Supposedly some engine had issues, but with me burning 15%-30% nitro content I have never had to do this..