Hold the throttle steady with your finger, if the hunting continues you have a carb or air leak problem. If it stops, the governor is the culprit. Check your top speed with a tach, it should not exceed 3750 rpm. It will hunt if over speeding.
From your description the governor gear inside the engine is working properly, if it comes apart the engine will scream just before blowing up LOL.

If I hold the throttle steady the hunting stops. So now what? I mean I am at wits end with this engine. I re-set the governor shaft and arm but might not have done it right for this engine. Throttle held wide open with all linkages hooked up, turn shaft opposite direction until it stops, tighten lock bolt. Best speed I can get is 2000 RPM before the surging gets starts to get real bad. I can hold the throttel shaft above that and it runs steady.

Rotate the throttle and note which way the governor shaft turns, likely clockwise. Loosen the clamp and turn the shaft in that direction with throttle wide open then tighten the clamp.
If the hunting stops when you hold the throttle, the carb is not the issue. Your governor is too sensitive.

Thank you Canguy, I did the adjusment just as you described still hunting. How can I make the governor less sensitve? I tried a stiffer spring (non Briggs) and a lighter spring (2 different Briggs OEMS for older units) but still hunts. This engine is the last of the flat head 8 HP which has the block like the older 190402 engines. I even took the governor arm carb and controls off of a working engine with the old flow-jet carb and the thing still hunted. Are ther service springs to correct this?

might try mownie's test of the throttle shaft and butterfly by itself...
take pix first to know how to correctly hook back up carb linkages. Then, remove all links so that throttle shaft and butterfly plate are isolated - then, "flick" butterfly plate with finger down thru carb throat, looking for no tight spots during shaft rotation and a free moving shaft to where the plate bounces back nicely from it's stops on it's own.
Sometimes the throttle shaft either gets worn or corroded and "hangs" just a bit setting up that hunting effect. To repair, either clean well (may have to remove plate/shaft) or replace shaft/bushings.
This test may/may not help. good luck.

I intentionally did not mention the possibility of a "tight" throttle shaft in this case because the OP stated he had the same problem with different carbs, and unless both carbs had been lying around corroding, I figured it must be something other than that.
But, it never hurts to check, at least if checked, it could be crossed off the list.

Mownie, Canguy, everone else, the carbs range from NEW to excellent working used. I noticed that 3 governor springs were used on this engine. One is for governed idle and the other 2 I guess are for all speeds parts 692136 and 263054. Part 692136 is the most interesting to me as it states it is "Yellow" the one on this engine is silver/metal color not a hint of any paint colors. SO maybe I have the Governed idle spring? Would make sense, trying to run it faster than the gov spring is made for should cause lots of hunting. I still do not understand why when I converted it back to the older 190402 configuration, using ALL the parts (carb, throttle control, gov arm, spring)from a great running 190402 engine, it still wanted to hunt. Different flyweights? Who knows. But I am going to order 1 each of these springs and give that a go. Thing is making me NUTS!! Should just convert it to an Air Vaine and be done with it, LOL. Keep the ideas coming and thanks.