We plugged them back in the day, one passage to intake, other is to exhaust. EGR connected the two with a vacuum diaphragm operated gate controlling...
I strip the wire end 2x as needed, fold wire upon itself usually once, remove plastic color with a twist, insert wire, lightly crimp to not break or...
I once found a set of screw extractors at HF, they have a tip that drills, then a fluted extractor like thread ... they use reverse so you just pick...