Just did about an hour of bush hogging in the pasture and didn't notice any problems until I dropped the engine to idle, it didn't have that clanky diesel idle, all most smooth. I thought it was just me. Throttled back up and it was extremely slow to come back up to cutting speed so I let it idle about 3 minutes and it was fine.
At first it scared me, I thought the compression was gone but after it idled a few minutes it was fine again. I've never ran it that long with a full tank before. Is it possible it vapor locked or more like vacume locked? since there was very little air in the tank. There is no visible vent in the tank is the reason I ask.
It wasn't over heating at all and the filter is good.