My 129 powered down while mowing...not sure why?

[three4rd]

Granted that I mowed really heavy stuff for close to 2 hours, and it's another pretty hot day. But still, can't recall this ever happening before. It simply throttled down and stopped. Then, couldn't get it started for about 5 minutes. Cranked ok but that's it. Finally started, but it was kind of limping along. Seemed worse with increased throttle so I kept at low speed. Luckily I was close to my house at that point. Governor seemed quite erratic though. Got it inside the garage, cleaned everything up from mowing. All looks ok underneath, and oil level's full. Tried again about 15 minutes later and it starts right up and sounds fine.

Are these old machines thermally protected somehow and so shut off when overheated? I'm thinking probably not but thought I'd ask. So then I guess I'm looking at possible carburetor issues.

New engine went in back in '15 and lots of other items replaced at the same time. Doesn't really get used that hard - maybe once every few weeks for 1 1/2 - 2 hours each time, but this time especially I had to mow through really heavy weeds.

See what happens next time I suppose but thanks for any suggestions in the meantime. Some quick research in older threads show others mentioning overheating with the suggestion that the coil might be going bad. Coil and all electrical components were new as of '15 with the engine replacement. Plug, air and fuel filters get replaced every spring. Grass screen gets cleaned before every mowing, as does the front grille (after each mowing) to make sure all those holes are open. I also clean around the entire bottom area - removing obvious dirt, etc. around the trans and filter. Hydraulic oil is routinely checked as well. Should have added that it was running great all the way up until when it stopped.