YT 6800 idle surge when PTO is off

Wondering if anyone has had this problem? Our tractor seems to run fine, when under the load of the PTO engaged, but surges when the load is off.

Also, we're experiencing sudden engine shut off, which I'm guessing is due to a blockage in the fuel feed. Engine restarts easily, after it cools off, and runs fine until the next sudden death.

Thanks for any comments. Tom