Thank you Jonas,
the fuel is fresh.. so i dont think is that.
Yestarday I tried to spry some ether around the carbs and i was not able to find any leak. May be there are, but i was not able to detect any.
As well, i tought that the issue could have been float bowls venting as i changes a well the 3 slotted fiber gaskets, but i tested the carbs without retaing nut so fully open to the atmosphere and no visible change, so i belive the floats breath normally.
may be the issue in the end is just that i am doing long static tests, and never did any tuning on the road as the car has no papework yet so can not go out.
And may be this flood the engine after a while. may be some soot builds up etc etc as the mixture is a bit rich, and in the end the engine stalls.
I will try to do the MOT techincal inspectio as is. and then try to fine tune it.