scag 23 hp kawaski eng , liquid cooled !

mower starts , won't go to 100% throttle every time . Sometimes adding small amount of choke will correct it for a while ! Sometimes after about an hour of cutting , eng will just shut down . this is an intermittent problem . new plugs look like maybe running a little rich . fuel pump pumping fuel ! I have blown through fuel line going to carburetor and will crank up . Could be coil maybe cooled down a little if breaking down when it gets heated ? Sometimes after starting , full throttle and engage PTO , you can tell it is not at a 100% blade rotation ! Any tips please !Also at full throttle with PTO off , eng will sputter through muffler like a "Miss" !

Thanks for info , kinda figured that might be it but now you convinced me . I can blow low pressure air to line from fuel pump into carb and it will crank and run for awhile !

On the Turf Tigers, there is a detent on the throttle control. If the throttle control gets a little bent (away from the assy), your speed will creep down. Also on this Kawai engine you can adjust the governor spring for higher RPM under load