First, if it's a 350F it's a 72-74 -- they became the 400F in 1975.
Need more info, though. Does it start back up? Right away or after a few minutes? Does it run rough? Have you tuned it up? How does it run through the rev range? Do you ride it at low revs? The 350F is meant to be ridden at higher revs, 4-5k is where it starts to pick up but you can rev them much higher.
What do the spark plugs look like? Is the battery good and charged?
What is "idle mode?" Idling, like stopped at a stop light? What is the idle set at. When you say stuck, what do you mean "stuck?"
Could be a number of things but narrowing it down requires more details.