The linkage going to throttle plate is the governor link that governor setup uses to regulate the engine. Unless you do a static governor adjustment the governor will never control the throttle plate in the carburetor. To set the static governor adjustment loosen the clamp screw at the governor bell crank. Rotate the throttle plate on the carburetor to full position while watching which way the governor arm moves. Then while the throttle plate at full throttle rotate the bell crank in the same direction until it stops. Now tighten the clamp screw. After this adjustment if the engine continues to run uncontrolled then it is likely he governor itself has failed.
As far as the carburetor you probably got a Nikki but don't know for sure as no engine model and type hasn't been posted. IF it is the Nikki even the fuel bowl gasket set can can it to leak especially has been apart recently and fuel line being mess with small pieces of rubber can have dislodge and now is now holding needle open.