83 750f1 sputter on WOT from idle

Bike is completely stock. When you pull it full throttle from idle in neutral, it sputters real bad. Gets a little better when the bike is hot. Symptoms: 2 of the pilot screws dont change engine sound or rpm when they are all in or all out. On those two cylinders, one pipe is turning blue, the other doesnt get hot as fast as the others.
Things i have tried:
New stock air filter from dealer.
Jets are spotless and are all the correct sizes.
Carbs are spotless and all passages are free.
New boots between air box box and carbs.
Checked for leaks at engine side boots with propane torch.
Carbs are synced.
New spark plugs- NGK B8ES

Any suggestions on where to look next?

Cranking the throttle wide open in neutral is very abusive to the engine and shouldn't be done. The engine should have a load on it (as in in gear - riding) when you open the throttle all the way up. Why would you even do that? Were you trying to make a video at the time like this guy?? :S

LOL i've seen that video before, and NO. i am not an idiot like that. I am not revving it to redline for shits and giggles, not revving to the redline at all. Its when you give it full throttle, it sputters. Yes it does do it under load, when your driving it. It sputters and bucks and then when it gets up in rpms, it snaps out of it and climbs smoothly.

You may want to clean and lube the timing advancer. If they get sticky they can create problems that mimic carb problems. Ed

does my 83 have a timing advancer? When I had the side cover off the motor all i saw was 2 pickup coils and such. It has electronic ignition. I know it still advances the timing, but isnt it done electronically on this bike?

Take a look at the Kawasaki.com diagram below. I have no personal experience with your model, but based on that diagram it appears your bike should have a timing advancer. Ed

hey everyone just an update. I found out my carb boots (holders) on the engine side were leaking. I had used a propane torch to see if the engine changed, and nothing. I sprayed brake parts cleaner and the engine almost died when I sprayed to of the cylinders. I ordered new boots and I will post back if it fixed the problem for sure. So, lesson learned, the torch method doesn't find leaks ass good as using a flammable spray.