i thought you said you had fixed this? if you can hear air coming back into the tank at a good rate then it's not plugged. just undo the fuel hose at the filter and blow with your mouth. if you can hear air passage with such low blowing pressure then it cant be that clogged. compressed air would really let you know how much air is passing by the sound.
1. unhook the fuel hose at the carb.
2. pour gas down the carb and start it.
3. if fuel squirts out of the hose you know the line,pump,filter are fine.
pay close attention to the fuel filter it will give signs. if the fuel in the filter is really low or fluctuates you have a air leak from the hose clamps. not all air leaks into the line will drip fuel out. change the old style wire clamps to new style.
also if you have a hitachi carb with the front window plate that has the little circle for a window change it out and find the full 2''x3'' glass plate from the older carbs to put in. then you can watch the fuel level in the float bowl much better. i find that alot of the hitachi inlet valves at the hose get stuck open or closed. if you dont have the big glass plate to look into tap on top of the inlet with a hammer as it starts to die. that will seat it temporarely for a moment. atleast you'll know your onto something good luck bro.