That is very interesting. While I wouldn't describe the mess out of the muffler as grey goo, it is dark-ish with some viscosity. I haven't flown in near that cold, maybe 45 F at the coldest.... (that's on the ground, dunno what the temp is 300ft altitude) I WILL check into this. Actually if it's true that might be why my tuning changes so much between days and between flights.

For all still interested:

I had an amazing thing happen. New Years day, a buddy and I put the plane on a stand and tuned it at the house. The engine ran marginally well as I am used to.... much improved over when I started this drama. We loaded the planes and the gear and went to the field. Temp was about 55 F.

We unloaded, assembled and he put his in the air. I started mine, it run ok, but I choked the engine before it warmed up and died. I tried to restart - nothing. After about 2 hours of fooling with the thing and methodically tuning, trying to stay within the previous needle setting, checking fuel tank lines, blowing through the lines etc, etc, etc. I wasn't moving fuel. I'd prime the engine by dripping fuel in the carb..... run, stop..... run, stop. Several guys come over, blah, blah, blah. I finally removed the LS stops and opened the needle one full turn! Blam fired up and run better than it ever had. What's up with that!?

I'm not an idiot (arguably), maybe inexperienced. I've tried to tune this thing very methodically by ear and with the pich test all over the needle settings and the stupid thing run marginally well at the settings I had, then not at all.

Anyways, it runs pretty good now. It still dumps a lot of fuel out of the muffler but it's making power like a .61 should. The transistion is pretty good, it's a little cold natured but nothing I can't handle.

Several posts up I removed the carb and cleaned very thoroghly(SP?) and I've had the engine running several times since then. The tuning was the same before and after the cleaning.

I'm still gonna play with it. And I will check the fuel delivery/pressure line blockage thing mentioned. Thanks for the link btw.