I bought a Fastrak with the Honda engine option. The unit had sat for a long time prior to sale, and the carburetor was recently replaced under warranty with a new unit due to an inability to idle smoothly. The mower now starts fine, and idles fine when cool. It runs like a champ, however when I idle down after mowing, it then surges significantly - almost cutting off and then sputtering back up. This is similar behavior to what it was doing before the carb replacement, and it only acts up when warm - after mowing. I am wondering if the fuel line inside the engine cover is getting too warm/hot and causing the issue. I plan to contact my dealer, but figured I would query the experts on this forum to see if anyone had any ideas. Anyone experience similar issues with the GXV610 engine? Otherwise, the mower is tremendous. PJ - I am in Pennsylvania - close to Everett. My local dealer who performed the work is Hines Equipment - great guys, excellent work.