This is an update to my problem with my 3W-140 B2F posted a few weeks ago. Thanks to all of those for there help, but I don't think I fixed the problem yet.

Here's the current situation:
At less than 2.5 turns on the low needle, the engine will not rapidly transition from idle to full throttle without quitting lean. It does run good at 2.5 turns on both needles. This setting should be way too rich, but it's not. A few flights ago the engine ran fine at 1-3/4 turns on both needles. Just for fun, I attempted to find the point where it was too rich. There is no change in performance from 2.5 turns to 5 turns on both needles. This tells me that something other than the needle valves are limiting the fuel flow. It performs the same with the cowl on or off. I have not flown the plane, and do not plan to fly it until I can get it to run at normal needle settings.

I have done the following:
Replaced the diaphragm.
Sealed all the surfaces between the carb and engine.
Opened the restricted exhaust to the stock muffler configuration.
Changed the Ams Oil 100-1 mix from 90:1 to 50:1.
Checked the screen filter inside the carb.
Checked the fuel system for air leaks.
Isolated the static pressure port by routing it into the fuselage.

Does anyone have any other suggestions before I replace the carburetor?

Thanks Cliff