That's normal, don't expect same throttle response as going forward. You have to move the lever slowly if you don't want it to go too fast, or jog it in and out of the lurch as you call it ,when backing down.
There's also nothing wrong with the lurch as you call it to get speed, if that's what you are after.
If you are going forward and want to back up, you realize you have to stop the boat first, so go ahead and lurch it. When I stop my boat at the dock so do I, especially with wind from the stern filling the sail created by the full canvas.