Part grabbing script moves when grabbed

i used the script in this video:

i modded it to fit my needs, but it goes very fast for a split second before going to the mouse, why does it do that? you can see when he grabs it it does the thing.i suspect it as something to do with the body gyro

Can you show an annotated screenshot or a clip of the bug?
“very fast for a split second” isn’t very descriptive.

you can see in the youtube video that when he grabs it, it get flung a little

I think it’s probably because the default target position of either BodyMovers are set to (0,0,0), which means it’ll teleport to the centre of the workspace for a split second.