Iíve got a 7 year old nitro slash, itís on its second 3.3 and Iím having some issues with the new motor after doing a proper break in.

I donít have a heat gun to take temps of the engine, but Iím pretty sure itís running cool enough... I richened up the engine after it started sputtering and falling on its face after 1/2 throttle, and that seemed to help. So I changed the glow plug thinking maybe that might have been some of the issues, but it is still having the same issues. I pulled the head off to make sure there was no issues, and everything is seemingly ok.

It runs great with a full tank of fuel, after about 1/2 tank it starts falling on its face, could it be an air leak in the tank?

Any help is greatly appreciated.