Thanks for pointing me in the right direction guys. I must have unknowingly removed some gum or a particle of some kind when taking the inlet needle out of the carb. I put it back and ran the engine. The slop on the bottom of the Extra is gone, and the idle is much improved. I can hold a steady idle around 1700 to 1900. It's not where I really want to be, but it will do for a few tanks to see if it improves.

While experimenting today, I could hold a 1500 rpm idle for a minute or so, but that nearly shakes the wheelpants off.

If I have any problems, i'll pick up a carb kit.