Hey, thanks for your reply :-)
I have been suspecting that the fuel accumulator could be bad. But it runs steady when it runs, and the misfire was worse when I had more leaks, to get it running i had to place a wrench opening the top plenum just slightly, and then the car would start right up without hesitation.
The car has been sitting for the last 12 years so there is probably allot of things in need of replacement, the fuel filter I changed a few weeks ago was from 1995 :-O
I found a vacuum line that went into the engine somewhere, most likely the one you describe, it's a bit larger then most of the lines around. It runs from that small tank looking thing on the front of the car, i disconnected it and found out that it did not hold any vacuum at all, like blowing trough å straw, so I found the leak, or at least one of them.
Tomorrow I will take a look and try to fix it,
Hopefully it will solve my problems :-D