sounds lean for sure take it back to the tuner as it sux paying for a tune thats not done correctly and if he's any good he will be more than happy to fix it for free but of cause make sure to check for an fix all the little things like air leaks first.
did ya get a dyno read out while you were there it may have a air/fuel ratio graph at the bottom also id love to know how much the big bad 300 puts out .