RE: tuning and running troubles
It might be a little lean at low throttle so try richening up the LSN. This will lower the idle slightly as well for a given carb gap. Cold weather will make a truck run a little lean because the cold air is denser.
Otherwise it could be that your clutch spring has just gotten a little stretchy (or broken) so replacing it might help - this will raise the rpm at which the clutch shoes engage.