John Deere 310G Runs Erratic Code F494

I have 2004 JD 310G that I recently purchased with 1300 hrs. It cranks easily and idles at 900 rpm. It had set up a few years due to previous owner health. It has a slight miss but barely noticeable. If you leave at idle after 3 minutes it starts running badly. Shut engine off and immediately start again and runs good for 3 minutes and does it again. Very consistent hot or cold. If running at higher rpm also runs fine for about a minute. Then if I shut off and recrank runs fine for a minute...

John Deere 310G Runs Erratic Code F494