I believe i have found the problem for my power loss, tough starts and rough accelaration.
A fuel lineending next to the brake master cylinder is not connected to anyting.
It has its own support on the master cylinderand is at the right place.
This fluid line seemcomes out from about the middle of the engine bay and has a tiny filter in it. Now I need to look for its connection !

But is this a fuel line for sure?

1994 XJ12

Thanks to all for your help and interest in these cars.

 

Now, I'm told vacuum. Efficacity??