I have a craftsman riding lawnmower with a kohler kt735-3075 engine that surges then stalls out when hot. 95 hours on the clock.

I’ve ruled out bad gas, fuel pump, carburetor, coils, spark plugs, collapsing hot fuel lines, having replaced them all with Kohler brand.

The seat detection plug is detached and wire comb removed

I’ve also tried setting a little choke when it surges. No change. Gas cap also loosened when surging. No change

I put a spark analyzer between the spark plug and boot that flashes when it sees a spark. Spark appears normal

I’ve also adjusted valve slap gap to .005 and coil gap to 1 business card thickness.

What are my steps to
Check next. This really has me puzzled.

The video was taken early on when not much was replaced. Same symptoms despite all I’ve done to it.

Surging is usually associated with running lean..
 
For S & Gs, with the engine running, try spraying carb cleaner/brake cleaner 
ALL around the intake manifold listening for any changes in RPM's. We're looking for
potential leaks / cracks in the manifold / bad gaskets, etc.
 
How do the spark plugs look? Both the same color,  normal (tannish), or?
 
Again, when acting up, pull the fuel line from the carb, route into a clear container 
and check for good flow.  If need be, set up a temporary container and gravity 
feed the carb by passing the tank/lines/fuel pump.
 
Lastly, did you check for spark when the issue IS OCCURING?
 
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