89 740 runs rough and ate a plug wire, twice!

[turbobrick23]

Just picked up an 89 740 turbo wagon (at). I did a compression test and got 115,125,125,130. I picked the car up for very cheap so it needs a bit of mechanical work. It idles very rough and accelerates decently to around 2k rpm but nothing after that. Its a bit loud (sounds like the exhaust manifold could be cracked but it looks fine) and sounds like a diesel truck. The car is only on 3 cylinders because the rubber boot close to the heat shield was melted right through which partially explains it being rough, but not it being loud? There happened to be a spare wire in the car so we tried putting that one on but again it ate right through the wire. It was a cheap generic wire (though looked new). Why would this happen? Is it from heat off the manifold, or an electrical problem? The plan is to get a new cap, wires and plugs tomorrow and see what happens. Also the plug tips are a bit white. Lastly, the boost tube from the airbox to the turbo has a small tube that connects, but its held on with tuct tape. I know this is a lot of info, and Ive spent a lot of time reading/searching, so I'd really appreciate any advice! Also are there any plugs or wires you guys recommend, or ones I should stay away from?