Thats pretty rare thing to happen on these heads, never seen one. I have handled pretty many of these heads during 40 years. They indeed come pretty long out in normal position so make sure at its realy loose.
Seem at kat versions has this EZ 200 K which looks information from knock sensor and lamda info and has no those pressure switches. I have some factory books about kat version. those are in germany lang but has good pictures.
Should be there? next to gauge sender? Number 3 is switch, note at for me it was stuck cause there was moisture which was reacting with sensor internals and rusted inside.
I made adapter from old plug, pipe and air connector. I would check timing and distributor gear play. Also distributor internals. Look with timing lamp if there inconstancy in spark and advance from idle to 4000-5000 area. I made one gear with slotting but it did not make realy difference with dani cam.
Fuel pump? Have you lamda to read afr? Stock turbo? Stock turbo exhaust side is too small to handle over 200hp specially that newer model which has smaller even than early models. Temp and back pressure comes high when revs go up.
From experience I would say at you need to replace head gasket. It will leak, surely you can try. I have tryed it several times, also tryed to cut that front from new gasket and used silicon in that connection point but no luck.
Have you checked detonation ecu box? I dont remember if its located same as earlier model, in earlier model its located under dash so at if heater valve is leaking it leaks directly to box and its not water tight. So in time it consume moist and starts fail. If its okay remember at least turn it so at connector is down to prevent it happen.