Like already mentioned above, make sure throttle trim is at neutral position.
If this is not the problem, check your idle gap, make sure it is not set too wide. Re-adjust to 1.0-1.2 mm (good for first start up).
Now richen (CCW) the low speed needle (LSN) a few hours at the time, until the idle speed drops to a point that is stable enough,
but the clutch does not engage (truck does not move forward).
Enjoy breaking in your engine
i adjusted the idle speed to the spec given, adjusted the throttle trim and it still takes off at idle. Anyway it could be slipper/bell clutch?