I forgot to ask how much fuel you have run through the motor. First off you need to tune on fresh fuel, when you are through using for the day run the tank dry or almost dry. I run my tanks dry but when I know i'm finishing I will let the motor cool a bit at an idle for a short while before it runs dry as opposed to being at full tilt then going dry. If i'm paying attention i'll stop the motor with my shoe or a soft screwdriver handle right before the tank runs dry. When the motor stops rotate the flywheel so the piston is down...you will feel no resistance then move it back up to just close the exhaust port...slight resistance. Reason for this is the piston and liner cool at different rates and I have good luck with longevity by doing this, but you don't have to.

It almost sounds like you may have a worn piston/cylinder which comes from normal wear or running too lean too long, but we'll decide that later. If that was my motor I would make sure I have good compression by ensuring the cyl head is properly tightened and the glow plug has a fresh crush-washer. What you will need to do is get the HS in the ballpark before you adjust the LS. The HS ultimately regulates the flow but is more delegated to mid and high throttle settings. On a full tank run the truck around a few minutes to get the motor warm, a warm crankcase helps to atomize the fuel. Make sure the throttle opening is open about 2-3mm when at idle, run the truck rich where it won't build alot of speed and turn the HS in 1/8 at a time until it runs good and doesn't die at high rpm's. When you take off does it stall or will the RPM's not drop enough? If the RPM's are still high at idle then richen the LS a tiny bit. If you get a miss at high speed open the HS up 1/8 turn and that should have you in the ballpark. If it stalls after running for a while and won't start back up and it feels like it has no compression you may have a worn sleeve.

Those traxxas motors do tend to run hot sometimes but if it is toast you may want to get the O.S. .18 which runs great with alot of power. How did you break it in and again how much fuel has run through it?