1864 intermittent shut off
 

1864 with the 18hp command, I can run the tractor for an hour + without the pto engaged and it runs just fine.
Engage the PTO and run it for 20 minutes and it will eventually die, to my ears sounds fuel related as you'll hear it miss a little then stumble and die. Restarts nearly immediatly, have to crank it for 2-3 seconds a couple times but fires right back up and runs for another 5-10 depending on load.
Haven't had a lot of time to diagnose. So far i've replaced fuel filter, fuel pump (previous owner sent it with the tractor) , and it's got a full tank of fresh gas, and I've ran it with the fuel cap loose to rule out the cap vent. I'm going to pull the filter and blast some air back towards the tank, make sure I don't have an obstruction between tank and filter.
Seems fuel related to me as it putters and dies, and can restart immediatly. I've had coils go bad and give similar problem but generally they need longer to cool before you can fire up again.
I've seen people say to check the fuel solenoid at the carb, can that cause the same issues I'm having? I'd think it's working fine as it starts and runs fine, fires right back up

I have had similar issues as the one you describe. Turns out it was
indeed fuel related. Had junk floating around in the tank itself. It would get
up against the fuel outlet and shut me down. After sitting for a while it
would settle and I could start back up. Just a thought.

Ken

Update to this.
Decided to go ahead and do headgaskets on the tractor this weekend. Figured pulling all the shroud and heat shields to do that job would give me good access to everything else.
Found I had a wire chaffed through that was under the plastic shroud on the back of the engine, purple wire that was worn through right where it was zip tied to the left side intake manifold.
After doing the head gaskets, pulling the carb and cleaning it, and fixing that wire she runs like a top.
Finding the broken wire was a bit frustrating. I got everything put back together, went to fire it up and instantly popped the fuse. Checked all the wires I could see, pulled and moved around some that you can't really see, after a couple rounds of that I got it to fire up without blowing the fuse. Mowed for about an hour then the fuse popped again. After that I decided to slide the engine forward and pull that back plastic shroud to inspect the wires you can't see under it. Wish that shroud was 2 pieces so you could pull the top half and not have to dig so far into it.