I'm not sure I would describe idle as unreliable. Unfortunately what happens is very reliable. If I start out with a high enough trim setting it will always drop by about 1/3 of the previous RPM after about 10 seconds. It seams just like I brought the throttle down to a lower setting. It doesn't burble or stumble, or wander around, it just drops. Once it does this it stays at that RPM indefinitely. If I start with a low RPM setting it does the same thing but because I started out low, it will drop about 1/3 and now the idle is too low and sometimes the engine will quit. I don't notice it at about 20% throttle and above. Engine doesn't have any issues with throttle advance or coming off throttle, just at idle. Help me to understand how this is related to a lean low speed setting and not a timing advance issue. Thanks for your help guys.