Help! Under almost any load, or high RPM, engine blowing alot of black smoke. Had carb rebuilt, accelerator pump rebuilt, plugs, ignition coils replaced. Still blows black smoke and can't handle a load. The only part modified was the plunger taken out of the broken fuel shutoff solenoid. I then plugged it with a screw (I thought for safety to keep gas out). It wouldn't run at all so I removed screw. I'm at a loss. Is there any way the solenoid without plunger could be causing this? What would the experts check next?

I removed the carb to clean it. In doing so, I did not pay enough attention as to which hole the throttle cable was attached to. I made my best guess and reassembled the carb to the mower. I can get the engine started, but it only runs with the choke on. As soon as I open the choke it dies. When it runs with the choke on, it hunts, shoots sparks out of the exhaust. Does this sound like a linkage assembly problem or something else? I did not remove the bowl from the carb or clean the needle valve, I only sprayed and cleaned the butterfly valves to loosen them up. Is there somewhere I can go to view proper linkage connections? I did not remove the governor linkage, only the linkage from the governor arm to the carb. Any help would be greatly appreciated.