T-max 2.5 engine issues
I had similar problems to you for a long time and it was quite frustrating for me.
What ended up working for me was setting the high end very rich. I ended up with my needles set at 2.5 low end and 4.5- 5 on the high end.
I don't think it's an engine problem, but more of a carburetor problem. I say this because I was at the track yesterday and a guy was having all kinds of problems with his T-Maxx. It turns out his was too rich and to get it to not stall when giving it throttle we had to bring the high speed needle all the way in to 2.75 - 3 turns out. Anything more and it would stall from too much fuel.
Also if the low end it too rich it won't start, it will just spit fuel out of the exhaust. On this guys T-Maxx we had it at 2 turns out and it was too rich and wouldn't start. With it at 1.5 turns out it would start with no problem.
Basically there is no standard setting for the T-Maxx. It seems that settings vary wildly from Maxx to Maxx. Also don't forget that temperature and elevation make a big difference in needle settings. The T-Maxx seems to be very vulnerable to any changes in the weather or elevation.
I think the internal engine problems people are starting to see is because of the wild tuning that they do to get it to run. They go from very rich to very lean and back which can be very hard on an engine.
The other fixes are to run a longer exhaust pressure tube (with a loop near the tank) and a longer fuel tube both that go around the back of the body posts to the other side of the engine. This keeps the fuel from heating up as much before it gets to the carb, which may be part of the air bubbles in the fuel lines that many people see.
It's frustrating but it can be worked out. When I had my T-Maxx at the track (in the process of trading it for two trucks) I was able to run a full tank time after time with out it stalling, unless the truck flips upside down and the marshals don't get to it quick enough.