Oil leak from underneath manifold

Three months ago I noticed oil dripping under my car listed above (mk3 CLX).
Upon inspection it looked like the oil pan or this gasket.
Upon pulling the car on a lift we found the leak to actually coming from up higher. Checked all seals, no leaks.
However, right underneath the exhaust manifold system at the rear of engine pools of oil leaking between the head and block.
I have had five people inspect the car including allowing them to drive it to feel if any power loss occurs, and it does often especially on long distances.
I am considering replacing all seals, gaskets, valves, all sensors and have the car rewired to perfection too. Just to make sure. It is driving me nuts knowing nothing but basics on cars and knowing by having to continue driving it like this I am damaging it further.
Please advise.
Oh, if this helps. Three mechanics have confirmed this car does not have a standard 1.8i top/head or manifold system. It is an aftermarket VW/Audi either 1.8i or 2.0L. I have seen the 1.8i. And it is smaller than my cars is.

Please I need help.