Help me identify this wire

[RxPx33]

I don't know a lot about engines but I am trying to learn as I go along. I decided to start by replacing the intake manifold and some other things on the engine. I came across this wire I know where it goes, but not sure the name of it. The cover around the wire is falling apart and I would like to either get a new sleeve to go around it or replace it all together.

So First can someone please tell me a name for this wire so I can find a replacement?

Second is it worth just re-sleeving or replacing the whole thing?

Lastly in the second picture I have these extra ports on the manifold. I found on the forums everyone is just plugging them, but no one said what they are using to plug them with. Any info on where to find plugs and maybe what size I need would be helpful.

Thanks