Piston Up and Down

I just wanted to make an piston ging up and down by itself so I just Starter trying some red stone technics.

At one Moment trying out stuff a piston didnt stop ging up and down so I tried to copy it.

1. Set a piston facing up. In top set a slimeblock at next to the slimeblock set a redstoneblock. And next to the piston set a redtone-torch/block so the piston is activated.
2.destroy the redstone-torch/block next to THW piston and watch it going up and down really fast.

Other aspects:
1. When you leave the world and go back it can be still going up and down or not.
2. Just wanted to mention I have minecraft forge and worldedit (could maybe be the reason)
3.Hope its the first report about this. If its not im sorry, just wanted to help ;D