i had the same problems that all of you are having , its the lsn. i got so frustraded that i took the carb off and put compressed air through it. this is what i did, i removed the carb, closed the hsn all the way in, closed the lsn all the way in now with a can or a compessor blow air through the fuel line opening and slowly open the lsn. you will notice that it will go past the flush mark by i would say 2 to 3 turns befor you hear air coming out. i found that if its flush there is no fuel coming in. then i marked that setting and did the same with the hsn and found it to be at 4 to 5 turns out from flush. now the truck idles with a gap at 2 to 3 mm.
hope this helps.