[DW]

check your fuel filters. Pinch off the fuel line by the tank and pull the filters and put a clean piece of hose on the back end of the filter and blow through it. If you can't get air through it after the gas is pushed out then it's clogged and needs replaced. If thats ok check the vac line to the petcock and try bypassing the petcock temporarily. If it starts and stays running, check the petcock end of the vac line to see if you have good suction. If thats fine replace the petcock. Also slowly take your gas cap off after it stalls and listen for a air hiss as you twist the cap. sometimes the vent in the cap stops letting air in the tank and creates a vacuum. It seems that the problem is your only getting a trickle of gas down to the carb. As the bike sits, without running the gas slowly fills the float bowl, the gas in the bowl gets used up and it acts like it's out of gas because your not getting a good fuel flow to your carb. I would check all that before I started buying parts. All this assumes you have a gravity fed system with the tank behind the seat. Is your air filter clean and the fat tube that runs to the back of the carb secure and leak free?