On the assumption that you are indeed using the choke in the correct way, and that it needs at least partial choke to keep it running at all times, then the most suspect problem source would be the slow/idle/pilot jets being plugged in the carbs. (Main jets provide little fuel at idle, unless the choke is applied.)
(You should also note if any head pipes are cooler than the others, as colder pipes point to specific cylinder issues or its related carb or spark.)
If the slow/idle/pilot jets are indeed plugged (you should verify this), then you have to determine why it is so. These jets have the smallest fuel orifices in the carb, and are usually the first to plug if anything other than fuel in in the carb bowls. You should work back toward the tank, look inside, is it clean in there?
Is the screen on the Pingle petcock clean? Is the screen intact? If you drain out the gas in the carbs, does it come out clean with no debris larger than 0.012 inches in diameter?
At what setting are your air bleed screws?
Lastly, what is the fuel level in the tank? Does the Pingle have a stand pipe for a reserve setting? Are you using the reserve setting when you have run problems. Can you verify that all the carb bowls are filling with fuel?
You should be aware that these engines need a tune up every 3 mos. 3000 miles. When was this last performed? If you don't know, or don't know that it was done correctly, it is due now.