Big Bear 350 carb troubles or ?

I recently aquired a Big Bear 350 2X4, that had been fooled with, mostly carb. I am fairly versed in air cooled engine, part of which included Yamaha Service back in the late 80s, After cleaning and fixing some common mistakes, float level, clean and soak carb, pressure test ndl & seat, fuel flow etc. It will start and run but at a warm idle it will occilate rpms maybe die or not takes a long while to return to idle, mostly random, It will restart OK, some times requiring half notch fuel enrichment. And yes I have: set idle mixture to 2 1/4, middle groove needle setting, vacuum test with carb cleaner, confirmed free operation of throttle cable its a single cable, Any ideas? possible valve adjustment? coast enrichment valve ? Trying valve adjust and enrichment valve today but any ideas or similar problems would be helpful. Otherwise it seems to run OK, no smoke, decent compression,good acceleration when it is running. Also will put in new spark plug today also!