This question has been asked several times, and usually ends up with the same answer. Most people don't seem to think that head temp is very important, till it happens to them.

If you scan the car forums you will find a lot more information and fixes for it.

I recently had this problem. I had the engine adjusted a little rich at full throttle, but would flameout within a minute or two after takeoff. I checked the head temp with a laser temp gun at the glow plug on the ground. It was readint about 350F. I had to richen the low side needle to get it down to 300F. The engine seems to like that better.