my neighbor said surging is usually a vacuum leak, said to mix soap and water in s spray bottle and hit around the carb and look for bubbles... bad idea?
My 2 cents...
I've never tried your neighbor's method but I'm curious if this how you checked for a vacuum leak?
Basically, I don't understand how bubbles would ever be created on the outside of the engine from a vacuum leak as the leak means that air is being sucked into the intake, so I would think that the soapy water would be sucked into the intake if there was a leak. This might create bubbles inside the intake at the leak site, but you wouldn't be able to see those, would you?
Generally, to check for a vacuum leak you use propane (unlit) or some spray liquid like carb cleaner. Something like WD40 might work too. You do need to be careful using carb cleaner or other liquids as some are very flamable, but that I think is the reason this works. If you get the propane gas near the vacuum leak it will draw in the propane and the engine will respond by increasing RPM or smoothing out as the air is replaced by the propane and it is burned in the cylinders.
For the spray method, like carb cleaner, the same thing will happen. Engine will pick up RPM as the flamable liquid is sucked into the intake and burned and as well, the liquid temporarily restricts the amount of air, or replaces the air being sucked in with a flamable liquid and enrichens the mixture.
Spraying soapy water? I think you are just cleaning your engine.

Not that it needs to be cleaned.
The plugs look like the engine is running lean to me as well. IDave mentioned this. I think you need to keep looking for a vacuum leak, or something else causing the lean condition like the carb. Maybe one of the carb's circuits is plugged or restricted. Maybe the jet size is too small. If it runs better when warm and the choke is on, then this is agood indicator you are lean.
The video you posted of the engine running also sounds like it's dying or stumbling from a lean condition.
I agree that the fan may help but my opinion is that it will be masking the real problem. It also looks like you are using copper for a fuel line. Perhpas this is stock, not sure, but copper is a great heat sink and I would think it could contribute to a vapor lock issue. Again, could be a secondary issue to deal with, not the primary cause of the problem.
Again, just my two cents.