Having problems with Scag 48" w/Kawasaki engine. Machine runs for about 15 minutes and stalls. Seems that the engine is hotter than normal. Changed fuel filter, sprayed carb cleaner in and around carb., emptied fuel tank and cleaned out fuel, changed spark plug and air filter, oil change w/ filter replacement. If I wait for engine to cool it usually starts back up. What can be making it run hot and stall? What can I check next before bringing to shop?