I have a Ford 1210. After mowing for awhile the engine will start to bog down sometimes to the point I have to stop and wait for a few seconds for the rpm's to work thier way back up. Then it will run fine for a few minutes and do this again. It has never done it before being run for 20-30 min. Only happens after that. Seems to happen more frequently if it is hotter out. Dosnt do it the winter when plowing snow at all (of course not mwoing and mower is removed). I am not familliar with diesel engines, but would liken this to a vapor lock condition in a gas engine. Anybody know what what be happening here ????????????????????