Losing mind jetting...

Cannot do much with info provided... we need to know pilot jet, needle, and needle position used. As well as air screw setting... also if you’re located at any extreme elevation that would be useful info as well... the bog you’re describing could be either a rich or lean condition... Also how does the plug look?

Air screw open two and a quarter turns (stock)
Slow jet #45 (stock)
Jet needle 6BEG20-68 (stock)
Needle clip position 3rd groove (stock)
Main jet 420 (380 stock)
Stock float level
New York state not sure about elevation
Run 93 octane pump gas with 927 mixed 32:1
Plug looks clean like new..

Many people on newer KTM's (including myself) with the Mikuni have had problems with the jet block gasket. I'd suggest you replace that as a starting point, then check your float height. Those two things have solved most if not all my Mikuni woes. Pretty sure the older style Mikuni's use a jet block gasket that is similar. JD Jetting carries a upgraded gasket for the newer ones I know.

https://thumpertalk.com/forums/topic/1284669-mikuni-jet-block-gasket-fa…

Only thing I can find is a needle jet holder no jet block tmx01b mikuni carb...

This.
Bog problems when you "stab" the throttle are almost always pilot jet and air screw related.
To adjust your air screw properly, adjust your idle so the bike won't stall and start with the air screw at 1.5 turns out from all the way in. Turn the air screw inward until the idle misses, then turn it outward until the idle misses. Your sweet spot is exactly halfway between these two spots.
If the idle won't miss as you turn the screw all the way closed, your pilot is too lean. If it will not miss as you turn it out, the pilot is too rich.