It Cloaks at start and decloaks, i tried placing them manually, then created them with triggers with properties: cloaked and invincible. they spawn normal and stay normal. I modified energy count to 100% for computer player.

The obvious first: Make sure you have the tech enabled.
Computer players tend to decloak their ghosts when there's no threat. Especially when they run a melee AI.
I'm not sure how to prevent that, but you could try to create them in a secluded area, attack them and then move them to where you want to have them.

I tried moving them but they decloak, i enabled the cloak for player also. I put the ghost near enemy computer so it cloaks when it gets attacked so problem solved.
but my next question is how do you make the computer nuke multiple places at once, i set 4 locations and the comp seems to only nuke 1 of them and then run around in circles with other ghosts...

You can't. The AI can only handle 1 nuke at a time. Only solution is to use 4 computer players.

Hey, I have found a solution to this which will (probably) work for you. Keep in mind this method does require a bit of work to ensure it works; however it is impossible to uncloak (from my understanding)

Basically, all that is required is doing the disable doodad trick that cloaks units. I can't remember right off hand what the exact sequence is to do this, but when it is executed the ghost will have the cloak teched but, when clicked, won't uncloak. Don't take my word for it as it's been a while since I've tried, but I believe it was disable -> enable -> disable -> move?? probably not. but something like that, you can find it if you use the search function.

I do not guarantee that this will work for a computer player though as I've never tried it. Good luck.