Reply to gemdozer:
Like SJ you should have a governor probleme
the governor can be opened up to oil it and free it up if that is the problem.
Also check that the throttle lever on the carburetor is free to move through it's full range of motion from slow where the idle speed screw touches the stop to wide open. Idle speed screw isn't screwed in all the way is it?
Then when you replace the linkage from the governor arm to the throttle lever on the carb, the throttle control rod should be pulling the throttle closed. (the long extension on the linkage pin is toward the left side of the machine and the "hook" on the throttle control rod is past the pin so it pulls on it).
The throttle control rod blocks the governor from speeding the motor up to full speed when you pull out on the knob. When you push it in, it allows the governor room to speed it up and if you push the control all the way in, the governor has room enough to fully open the throttle under load to maintain set speed. It will normally keep the throttle closed most of the way until the clutch is engaged and the engine is loaded, then it will open the throttle a lot more.
The governor is pretty simple, there are flyweights in the pulley that push on a rod through the middle of the shaft and work the lever coming out the back, The spring pulls the arm toward fast and the weights stretch the spring and push the arm toward slow.
You may only need to spray the governor arm where it comes out the back cover and work it back and forth. If that doesn't get it, remove the back cover with the arm and the front cover on the pulley to oil and free it up. when you button it back up, with the governor sitting horizontal, fill the pulley with oil until it runs out and replace the cover.
D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time😄