I ran the tractor yesterday and it shut down after an hour or so. The engine RPM's drooped until it shut off. I got it to restart a couple times but the RPM's never got high enough to drive it. There was no response to the throttle. The throttle linkage is intact. I put on a new fuel filter the day before. I'm not sure at this point what the problem could be. Any suggestions as to what I can check ? Thanks for the help