Im not 100% sure i understand the question, do you want to move the whole model at once or random parts from the model ?
The reason the parts arent in sync is because you are choosing a random part each loop and moving it
If you are trying to move the whole model at once you can either use SetPrimaryPartCFrame or loop through all the parts and move them individually,
dont use SetPrimaryPartCFrame if you intend to move the model by a lot and often as floating point errors make the model drift apart slowly.
Normally, if you want to move a model around on the server, with all of its parts staying oriented the same relative to each other, you weld everything together and use some type of body mover on one of the parts.
There are some special cases where you might want to use SetPrimaryPartCFrame() to move a model, but this is generally when you want to move it in a single jump and you don’t have anything interacting with the model that isn’t welded to it. For example, if you have a tool to place furniture in a room, cloning and CFraming the models into position is fine.
But it’s not usually desirable to do server-side animation by setting CFrames, for a couple of reasons. One reason is that the resulting animation runs at replication rate which is not a nice smooth framerate. A model moving with body movers gets client-side interpolation so that it animates smoothly at the rendering framerate. Another issue with CFrame animation is that it doesn’t interact with physics simulation the way you might expect, for example, a player standing on a CFrame-animated moving platform will not move with the platform, it will slide out from under them; as far a the physics system is concerned, such a platform does not have velocity, it’s making discrete, instant jumps (mini teleports).
Definitely what @Crazyman32 said… but if you are doing it many many many times, then it will slowly get offset so all your parts won’t move in unison (here is where I found that info: (PrimaryPart_CFrame_Error) But I’ve never had the issue so you’re pretty safe with it.