UPDATE!
Ok, changed spark plugs yesterday.

Cursed a lot. there is absolute no room for any tools on the drivers side cylinders towards the firewall.

The plugs were missing the center electrode, on all of them. Guess they needed a change.

Now the car is pulling fairly, although i still get a small "delay" in power when exceeding 120 mph. (of course this is tested on a closed circuit ;-) )
Today i will try to change fuel filter as well.
Tomorrow my new setup of EBC brakes will arrive so that i can stop again.