I had a similar issue. When I step on the throttle/foot pedal, It would not hardly respond until I got moving a little and then whamo, it takes off. I see yours wont respond properly until you get more speed. Not sure if its the same issue but mine was my throttle,,, its a Throttle Position Sensor fault,,,TPS. The footfeed is electronic,, I replaced it and all is well. Best of luck.