problem after changing tanks

High wing or low wing? Especially if the latter, I suspect a pretty bad air leak in the fuel system upstream of the pump. These lines are under suction. The diaphragm will pump air just fine, so fuel pressure will read just fine. But the carbs will get a fuel "foam" full of bubbles. A small leak will cause some problems, but the engine will run. A bigger leak will start causing "misses" at high power. A biggest air leak will cause exactly what you describe. Why? Pumping capacity increases with rpm. Even though near idle rpm isn't demanding much fuel, the pump has limited flow capacity and its delivering more bubbles than fuel. The bowls empty and the engine stutters. Increasing rpm overcomes this up to a point, filling the bowls. Back at near-idle, say 2,500 rpm the engine will run smoothly for a while until the bowls empty again.

Yes, learned this the hard way. Don't expect to find a wet fitting. My air leak was coming from the shaft o-ring of the tank selector with no obvious leak evident.

Thanks for input.  I eneded up finding the problem was not related to the tank change.  My choke cable on one side was adjusted too tight and the choke spring was not able to pull it to the stop.  I am not sure how that happned during the tank change but after making that small adjustment, it runs fine.