Sorry, when I said "needle," I was referring to the plunger, the shiny part of the solenoid that you show in your picture. The symptoms that you describe DOES sound like an issue with this function of your fuel injection system. Intermittent issues like this are very frustrating. Many a wild goose chase has been launched by such a scenario. Hey, I wonder about something. When you are underway and the bike is stalling, if you rev the engine when you clutch to keep the rpm's from dropping, will the engine will still stall? If revving the motor to avoid the throttle body from closing avoids the problem, then another big finger points to the idle situation.