Found it !!!

My final guess was that the problem wasn’t to find in the carburetors but probably in the ignition causing the misfires.

So I called a friend who had some spare ignition parts and I changed the ignition module and coil and all the symptoms disappeared.

  After this I changed the friend coil with my special Moroso coil and the misfiring was there again; so it was the brand new coil that caused the problem all this time.
The resistor was Ok it was only the coil going crazy from time to time.