Basic engine tuning for noobs

[soane]

Two guys I work with have both bought second-hand Traxxas T-Max trucks, both in good nick but they can't seem to set them up properly. They've followed the instructions on the Traxxas website for basic set-up which consists of screwing the high speed needle all the way in (full lean) then 4 turns out as a 'base' mixture then setting the low speed screw flush with its housing and finally the idle as low as possible. The problem is neither car will run for more than 5 minutes without stalling. Now from what I can gather from the website and of Youtube, a too-lean mixture will cause stalling, yes? All I'm after is some pointers (my advice is to go brushless ). Thanks in advance.