I would take the engine apart and give it a good clean,then put all together and return it to factory settings and I would make sure that engine has no leaks and that glow plug is working perfectly,then I would make sure that the fuel is fresh and then I would put the engine back into a T-Maxx and heat it with a hair drier for few minutes till it get really hot,then let it cool down a bit and try to start it on factory settings and also I would check the clutch and gear box to check if anything is broken or loose,then if the engine starts and the truck is running nicely I would tune the engine for best performance & life or just get new 2.5...