With the Losi fuel tank mod I could run at race speed for 15 minutes. Now the engine just stops around 5 minutes. Then it is hard to start and will not idle. The engine revs and dies then revs and dies. It sounded like an air leak so I replaced the fuel tubing and pressure line. I even changed the fuel tank. Still does it. The carb is cast into the crankcase so there is nothing to seal there. I am thinking bearings. The car does run real strong until it shuts down. I posted the problem on the engine thread. I am getting frustrated.