its hard to say, it may be loading with fuel at idle so it bogs down if it is too rich, it may not have enough fuel so it cuts out from an idle, i would suggest richining the lsn a little at a time and see if it helps, if not try start leaning it, i would think its probably too lean since you say it starts easy, when they are too rich it usually floods out. make sure you run the car a minute to let the adjustments start to work. before you turn the needles more