kohler V600 stalls out after about 30 minutes of mowing, changed the oil,air filter.

[jeep3363]

I can't figure it out. it starts back up and runs ok after a bit.

 

[bertsmobile1]

Three things to look at
1) Coils getting hot and breaking down
2) debris in the fuel tank blocking off the outlet.
3) debris build up on cooling fins causing over heating
There are others , but these are the most common

 

[ILENGINE]

And depending on year of mowers, possibly a clogged vent in the fuel cap.