[Tf175]

I would look at fuel shut off solenoid on top of governor . The plunger moves out to push the lever to shut down the engine . 

Overheat safety  system will shut engine down , you would have warning light and high temp reading , etc .
Presumably this system could fail , shut things down in non overheating situation .

Is your engine a DDEC ? I don't know when the electronic engine controls started coming in Newells .

Last thing touched always suspect , but seems like you did some miles after filter change ?
Certainly look at filters , never know . 
Chris