Troy Bilt Mustang rzt won't start unless I do this

[Pigsticker]

I have a Troy Bilt Mustang RZT mower. It has the Kohler engine and has been a good mower up until last summer. It will turn over but it will not start unless I stick a long screwdriver through the air filter housing and hold the throttle plate open. I'm usually pretty handy on things like this but this has me scratching my head. I've replaced the carburetor with a brand new one. The carb solenoid is working. I've replaced the fuel pump and the fuel lines are clear. It's getting plenty of fuel. When I hold the throttle plate open and it starts, it runs like a top. What could this be. I've noticed the linkages are linked to the governor. Any ideas?

 

[ILENGINE]

Lets start with what Kohler engine your have on your mower. Model, and specification number from the engine is what is needed so we can assist you.

 

[bertsmobile1]

Engine numbers would be a good place to start so we have an idea about what motor we are dealing with.
The throttle plate is the one closest to the cylinder, the choke plate is the one closest to the air filter are you really holding the throttle plate open or the choke plate ?
The throttle cable should be holding the throttle plate open when the engine is off.
The choke plate is held open by a clock spring under the butterfly lever.