Diesel in gas engine, surges after cleaning

[Risueño]

My boys accidentally put diesel in our Koehler 26 hp 7000 Series engine. After draining diesel from the line, taking out spark plugs and getting it going, it now surges at idle up to half throttle. Any ideas? This has the Smart Choke. Seems it running lean. Are there other places between the tank and carburetor that could be restricting fuel or is my Smart Choke acting up?

 

[bertsmobile1]

Did you take the tank right out ?
many of them take off slightly above the floor to avoid sucking up dirt & debris .
Thus there will be 1/4" or so of diesel in the bottom of the tank.