Misfiring issue

So recently i bought a used favorit carburetor and i rebuilt most of it and all new gaskets and new base flange and gaskets (the new type) first issue was the idle cut off valve was not working. So i installed my old one from the original one as i could not find a new one. The felicia valve has a slightly different shape and it has more holes than the favorit one. When i screw the cut off valve all the way and tighten it the engine stops, So i left it a little bit loose and it seems to be running fine.

The only issue that remains is that when i start it first thing in the morning the engine will misfire for 4-5 seconds then it will fast idle normally.

I want to add that i adjusted everything by the book. And for the sake of it i removed and regapped the spark plugs to 0.9MM as one of them especially was almost hitting the electrode it was so close