Engine was sitting so long with the after run oil in it, that it turned to gel. The exhaust valve was pretty sticky and I lubed the engine with Zep 45. Works great. I rebuild and tune many, many engines. Not a noob, but definitely don't kow everything. New Mojo 60 profile. New lines. New tank. Glow plugs have been changed as a "why not" method. No fouling issues. I didn't have YS 20/20 on hand at the field last weekend, so a friend put in a tank of his last year old stuff. Its been working just fine in other models and I had a tank of it. Untill last night. I pulled out the last ounce of that and put in Wildcat 20%. Less oil, but great to test with for comparision. I was able to keep an idle for about a minute and half. Probably around 3000 rpm though. I am going out to the garage in a bit to retest outside in daylight where I can get a good tach reading. Prop is a 15 x6 APC. Going to run a 16x6 IF this engine is worthy. Ihave a feeling like I'm chasing the needles, or something really strange is going on. Hence the question of running a hotter plug. I can run the engine at half turn out to 4 turns out on the low end and the only difference is when its richer it smokes more. At 4 turns out, it is slightly higher in idle speed