Sorta O/T: Lawn Tractor Issues

Afternoon Folks,
I was over at work today (www.trecothiccreektrains.org) mowing the lawn in preparation for tomorrow's events, and I got about half-way through the mowing, and the tractor started acting funny...at idle, it ran fine. Throttling up to WOT actually slowed the motor down (At least, it sounded like it did...), and caused a significant loss in power. Pulling the choke lever out to about 75% brought it back to nearly full-power, and sped the engine back up, but caused large clouds of smoke, and a very noticeable smell of gasoline. I only ran it like that long enough to get it back to the building. While it was sitting there, I wiggled the spark plug wires, removed the air filter to be sure it wasn't clogged, etc, but I'm not that familiar with the motor in this tractor, and given the lack of a manual, I opted to not bother going into more in-depth troubleshooting procedures.

The tractor is a Sears Craftsman from ~2000, with a 42" cut (dual-blade), and a B&S V-twin putting out either 21 or 22 horse. Battery is under the hood, fuel tank is under the seat.

If anyone has any suggestions or ways to troubleshoot, I'd be happy to hear them.

Thanks in advance!
AR

Sounds to me like bad gas.

Check the fuel system for clogs... Pull the fuel line off at the carb... does gas pour out? Now use your mouth or an air compressor and blow hard into the fuel line... does the gas pour out even faster now? if so you have a clog somewhere in the fuel line, check the fuel filter and tank for dirt.

If it doesn't have a fuel filter the first thing you need to do is take the carb apart and clean it.

PS... did you check to see if the air hole in the gas cap was working? It could be as simple as that.