You're probably right about the fuel pump. Yesterday I went and picked up some new jets (in case I need to replace the pilot), came home ready to dig into this, fired up the bike to check the issue and... no issue: it didn't die once. WTF. So I took a break and am going to look into it today but obviously its an unreliable problem. Maybe there is some gunk that is vibrating into the pilot and intermittently blocking it?