I think, at this point, it is a good idea to isolate the problem....many fool around with carbs only to find the problem was electrical all the time. Make sure any resisters within the ignition circuit are good....some makers used to put tons in to stop radio and tv signal interference. A fully charged battery is also a must with todays electrical systems being so sensitive to voltage drop. Make sure any sensors are connected...clean the terminals if needed. Check all the fuses for security and cleanliness all relays too...esp ones that are specific to the offending pot...some times just wiggling these can cause problems.
Good luck