KZ400 Single Carb Woes

Have a 79 KZ400 that was never satisfied with the stock carbs, no matter how many times it was cleaned, balanced and tuned so I got tired of messing with them, yes even by a shop. Got an 11th Hour manifold and a VM34. 

Bike runs AWESOME when WOT, lots of power, and dare I say feels quite a bit more peppy over stock carbs; however, at anything less than 4000 RPM the bike stutters and sputters underload ONLY AFTER first exiting said load (i.e. shifting, coming to a stop, etc).

The idle is all cattywampus: sometimes wanting to stall at 800-900RPM, sometimes idling PERFECT at 1100 RPM, sometimes idling high at 1600-2000RPM, sometimes it will randomly rev to 3500-5000 and hang there for several seconds. Majority of time the idle is constantly surging 1200-1500. Reminiscent of a vacuum leak, but I cannot find any (sprayed head-to-manifold, manifold-to-boot, boot-to-carb, carb-to-filter as well as choke areas. NO LEAKS. Throttle cable is not binding, slide is fully closing.

The bike was running perfectly fine last year before winter. YES I have cleaned the carb and did so to the extent of spraying every tube and orifice, including removing the choke assembly cleaning that pocket out as a just in case. The tank has ALL brand new gas and ZERO sediment/crud. At this point I'm at the end of my wits. Bike was fine last year with the same jetting but now is only  at 5k+ RPM. Only making me contemplating getting a modern bike to ride more and more (eyes set on a Z400 with fuel injection). My roommates told me to throw some StarTron in there as it apparently works miracles on small engine machines (he used to work for a repair company), but other than that, I'm out of ideas short of getting a color tune.

Pilot jet: 27.5
Needle Jet: 159-Q0
Needle: 6F9
Main jet: I wanna say 140, but don't remember (it's somewhere between a 130 and 190)
All else: stock (slide, air jet/screw, etc)

Gonna throw some new plugs in when I get home as a just in case.

EDIT: to mention that bike also felt like it was running EXTREMELY hot for some reason. It was only 50 degrees outside, ran for 15 minutes.

So just an update, I pulled a black and it was entirely black. So I guess while it ran fine last year, the plugs are probably fouling this year as a result. I'm gonna be dropping the pilot and just start over with tuning LOL
If I can find the jets I bought last year, I'll have access to a 15, 17.5, 20, 22.5 and a 25 pilot. Debating whether I want to start over with the 25 or just step down to the 22.5...

Did you check the ignition timing and is your timing advancer moving and not stuck by rust?

They were fine last year when I checked the gap on my points. Never hurts to double check though. Will do tomorrow. I don't get off until 730 and have maybe 20 minutes of light at best by the time I get home.