Does the engine stop suddenly (like you turned the key off), or does it act like it ran out of gas (as in...it stutters and stammers and dies)?
Does the engine start right back up readily or does it require some amount of cranking with the starter before it gets running again?
Does this tractor have an electric or a manual type of PTO?

Without having a schematic to view, let me ask this also.
If you lock the parking brake on this tractor, will the engine crank up and run without you being seated on the tractor?

Please post the technical model number of the tractor that you might find under the seat. That number might enable one to view a wiring schematic for this tractor online.

In MOST tractors, this would indicate a bad, misadjusted or disconnected seat switch.
Honda "sometimes" does things differently, but without a schematic it's hard to say for sure.

Do check out the seat switch on general principle for anything obvious. though.

Thanks for the info, I do believe it has something to do with the seat switch. Thanks for answering and putting me on hopefully the right track on solving this issue.