Walk behind Exmark Lazer Z Throttle/governor issue

I have a THP19KAE483 Exmark Lazer. It has a Kawasaki FH580v. When you start it first thing in the morning, it starts fine and runs fine, however as the day progresses and engine gets hotter each restart comes with a high speed rev that has to be tamed by moving the throttle up and back which then settles engine back down and back to normal. You shut it off and start right back up it will do the same thing. I have adjusted throttle linkage and governor adjustment and double checked it. I'm at a loss. Any ideas greatly appreciated.

http://www.mymowerparts.com/pdf/Kawasaki-Service-and-Repair-Manuals/ your engine repair manual is 12 down.